Don’t use file_get_contents for HTTP urls it is a HUGE SECURITY RISK.
A LOT of hosts will drop this attempt (often silently)
Please use cURL instead.
$ch = curl_init('https://api.twitch.tv/kraken/streams/' . $channel );
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
$r = curl_exec($ch);
curl_close($ch);
$request = json_decode($r);
That is quick and nasty but will get you going.