Calculating number of occurrences in array

You have some issues in your code. First of all, the logical mistake you made lies here:

if($gameID !== $newGameID)

The if block will only be executed when the game ID changes, which of course only happens for the first entry for every game ID. That's why only the draw votes are correct.

Then there are some variables that you have never declared (e.g. $newGameID). This will yield a notice and is bad (even if you don't see it because display_errors is probably set to 0).

Furthermore, all your isset()s like here:

$homeVotes = $nrVotes;
if (!isset($homeVotes)) {

are pretty useless as you're declaring the variable right before, so !isset() will always evaluate to false.

I'd personally go for an array in this situation and do something like this:

$arr = array();
$currentGameId = -1;
foreach($results as $result) {
    $gameId = $result['gameID'];
    $homeTeam = $result['homeTeam'];
    $awayTeam = $result['awayTeam'];
    $pickedTeam = $result['pickedTeam'];
    $nrVotes = $result['nrVotes'];

    // initialize new subarray if game id changes
    if ($gameId != $currentGameId) {
        $arr[$gameId]['homeVotes'] = 0;
        $arr[$gameId]['awayVotes'] = 0;
        $arr[$gameId]['drawVotes'] = 0;

        // remember current game id
        $currentGameId = $gameId;
    }

    // add votes
    if ($pickedTeam == $homeTeam) {
        $arr[$gameId]['homeVotes'] += $nrVotes;
    } elseif ($pickedTeam == $awayTeam) {
        $arr[$gameId]['awayVotes'] += $nrVotes;        
    } else {
        $arr[$gameId]['drawVotes'] += $nrVotes;
    }
}

This will give you an array with the game IDs as index like this:

Array
(
    [127] => Array
        (
            [homeVotes] => 2
            [awayVotes] => 0
            [drawVotes] => 2
        )

    [128] => Array
        (
            [homeVotes] => 2
            [awayVotes] => 1
            [drawVotes] => 1
        )

)

As billyonecan mentionned, your problem is

if($gameID !== $newGameID)

If you look at your array data, you'll notice that $results[0] is the first occurence of match 127 and it gives the amount of draw votes. Your if statement will make $results[1] and $results[2] be ignored. The same thing happens with match 128 and so on.

The way around this is to declare your variables first, and every time you change game number, you echo your variables and then reset them (don't forget to use the information contained in this line or you'll be missing a value);

Your code would look something like this:

<?php
function output($homeTeam, $homeVotes, $awayTeam, $awayVotes, $draw, $drawVotes){
    echo $homeTeam . ' Number Of Votes = ' . $homeVotes;
    echo '<br />';
    echo $awayTeam . ' Number Of Votes = ' . $awayVotes;
    echo '<br />';
    echo $draw . ' Number Of Votes = ' . $drawVotes;
    echo '<br />';
}

$results = array(
    0 => array('gameID' => '127','homeTeam' => 'Wales','awayTeam' => 'Scotland','pickedTeam' => 'Draw','nrVotes' => '3'),
    1 => array('gameID' => '127','homeTeam' => 'Wales','awayTeam' => 'Scotland','pickedTeam' => 'Wales','nrVotes' => '1'),
    2 => array('gameID' => '128','homeTeam' => 'France','awayTeam' => 'Ireland','pickedTeam' => 'Draw','nrVotes' => '1'),
    3 => array('gameID' => '128','homeTeam' => 'France','awayTeam' => 'Ireland','pickedTeam' => 'France','nrVotes' => '2'),
    4 => array('gameID' => '128','homeTeam' => 'France','awayTeam' => 'Ireland','pickedTeam' => 'Ireland','nrVotes' => '1')
);

$homeVotes = 0;
$awayVotes = 0;
$drawVotes = 0;
$newGameID = $results[0]['gameID'];

foreach($results as $result){
    $homeTeam = $result['homeTeam'];
    $awayTeam = $result['awayTeam'];
    $draw = 'Draw';
    $pickedTeam = $result['pickedTeam'];
    $nrVotes = $result['nrVotes'];
    $gameID = $result['gameID'];

    //CHECK IF NEW MATCH OR SAME MATCH ON ITERATION
    if($gameID !== $newGameID) {
        // New match, output and reset
        output($homeTeam, $homeVotes, $awayTeam, $awayVotes, $draw, $drawVotes);
        $homeVotes = 0;
        $awayVotes = 0;
        $drawVotes = 0;

        if ($homeTeam === $pickedTeam) {
            $homeVotes = $nrVotes;
            //homeTeam Got 0 Vote
            if (!isset($homeVotes)) {
                $homeVotes = 0;
            }
        }
        if ($awayTeam === $pickedTeam) {
            $awayVotes = $nrVotes;
            //AWAY Team Got 0 Votes
            if (!isset($awayVotes)) {
                $awayVotes = 0;
            }
        }
        if ($pickedTeam === $draw) {
            $drawVotes = $nrVotes;
            //Draw Got Zero Votes
            if (!isset($drawVotes)) {
                $drawVotes = 0;
            }
        }

    }

    else {
        // The same match

        if ($homeTeam === $pickedTeam) {
            $homeVotes = $nrVotes;
            //homeTeam Got 0 Vote
            if (!isset($homeVotes)) {
                $homeVotes = 0;
            }
        }
        if ($awayTeam === $pickedTeam) {
            $awayVotes = $nrVotes;
            //AWAY Team Got 0 Votes
            if (!isset($awayVotes)) {
                $awayVotes = 0;
            }
        }
        if ($pickedTeam === $draw) {
            $drawVotes = $nrVotes;
            //Draw Got Zero Votes
            if (!isset($drawVotes)) {
                $drawVotes = 0;
            }
        }
    }
    //CHECK FOR NEW MATCH
    $newGameID = $result['gameID'];
   }//foreach

   //This line outputs the last match which would not be output otherwise.
   output($homeTeam, $homeVotes, $awayTeam, $awayVotes, $draw, $drawVotes);
?>

The if statements that are used to update the values should be put into a function in order to avoid replicate code. Hope it helps