Absolutely! StreamYard bypasses Youtube's subscribers requirement for live streaming, so you can have any amount of subscribers to live stream on desktop or mobile.
Note: If you want to stream from YouTube's mobile app directly, Youtube Live requires that you have 1,000 subscribers. Streaming from StreamYard bypasses this rule because you are not using Youtube's mobile app to stream, even if you are using your mobile device on StreamYard. Keep in mind that there are additional restrictions on live streaming on YouTube here.