Ever since Youtube Gaming was the exclusive platform for ESL Pro League matches, the number of viewers has drastically reduced. That being said, Twitch is pretty famous for its bots, most of which are the members of some of the biggest channels.
Youtube Gaming has seen a drastic drop in the number of live viewers. Live Viewership is the sole parameter for most of the sponsorships coming into esports. Brands want to associate themselves with the big numbers and esports channels have seen some amazing numbers with respect to streaming.