how to optimize if else statements

According to your if check there is no need for an if check because if $value->name == '' you are saving empty string in $user->user_first_name = '', so you can remove if check

$user = new User();
$user->company_id = Auth::user()->company_id;
$user->user_label = 2;
$user->unique_id = $value->userid;
$user->user_first_name = $value->name;
$user->card_id = $value->cardnumber;
$user->save();

Edit for updated code base you could refactor your code as

foreach ($remote_user_detail as $value){
    $user = User::where('unique_id',$value->userid)->first();
    if(count($user) == 0){
        $user = new User();
        $user->company_id = Auth::user()->company_id;
        $user->user_label = 2;
        $user->unique_id = $value->userid;
    }
    $user->user_first_name = $value->name;
    $user->card_id = $value->cardnumber;
    $user->save();
}

As Khalid pointed out you don't need to check as you're already assigning empty value so it's a waste. This solution is only intended If you want to add anything else.

Just use Ternary opertor on the $user->user_first_name like

            $user = new User();
            $user->company_id = Auth::user()->company_id;
            $user->user_label = 2;
            $user->unique_id = $value->userid;
            $user->user_first_name = ($value->name=='') ? '' : $value->name ;
            $user->card_id = $value->cardnumber;
            $user->save();

May be like this ?

$user = new User();
$user->company_id = Auth::user()->company_id;
$user->user_label = 2;
$user->unique_id = $value->userid;
$user->card_id = $value->cardnumber;
if($value->name=='') {
    $user->user_first_name = '';
}else {
    $user->user_first_name = $value->name;
}
$user->save();

I recommend you create a User constructor, and just pass in the user as parameter 1, and $value as parameter 2

class User {
    //definitions here
    function __construct2($user,$value) 
    { 
        company_id = $user->company_id;
        user_label = 2;
        unique_id = $value->userid;
        user_first_name = $value->name;
        card_id = $value->cardnumber;
    }
}

This highly cleans up the code for future use, if wanting to reallocate something like this.

$user = new User(Auth::user(), $value);

Also, as shown -- no if statement is needed

How I see in 2 condition $user->user_first_name is always equal to $value->name. See your self if($value->name=='') {$user->user_first_name = ''} So just write your code without if else.

$user = new User();
$user->company_id = Auth::user()->company_id;
$user->user_label = 2;
$user->unique_id = $value->userid;
$user->user_first_name = $value->name;
$user->card_id = $value->cardnumber;
$user->save();

Also, one advice for the feature if you have if else situation use PHP 7 Null coalescing operator here is the link and example

http://php.net/manual/en/migration70.new-features.php#migration70.new-features.null-coalesce-op

// Fetches the value of $_GET['user'] and returns 'nobody'
// if it does not exist.
$username = $_GET['user'] ?? 'nobody';
// This is equivalent to:
$username = isset($_GET['user']) ? $_GET['user'] : 'nobody';

// Coalescing can be chained: this will return the first
// defined value out of $_GET['user'], $_POST['user'], and
// 'nobody'.
$username = $_GET['user'] ?? $_POST['user'] ?? 'nobody';

 foreach ($remote_user_detail as $value){
            $user = User::where('unique_id',$value->userid)->first();

            if(count($user) > 0){
                $user->unique_id = $value->userid;
                $user->user_first_name = $value->name;
                $user->card_id = $value->cardnumber;
                $user->save();
            }else{
                $user = new User();
                $user->company_id = Auth::user()->company_id;
                $user->user_label = 2;
                $user->unique_id = $value->userid;
                $user->user_first_name = ($value->name=='') ? '' : $value->name ;
                $user->card_id = $value->cardnumber;
           $user->save();
}
}

now how should i optimize this if else because unique id user_first_name and cardnumber are same