Amazon has for years been saying that they think that Twitch is under monetized. In their minds, 20% of watch time could be ads, just like regular TV. Streamers don’t like ads: it kills the vibe when your audience gets a 2 minute timeout. So streamers aren’t running enough ad breaks, and try to support themselves via memberships, merch and other alternative monetization methods. And for some, Twitch is only advertising for the real money-maker on another site. So Amazon doesn’t get the ad money they think they should get, and they only get a cut of memberships.
So then it’s a question of how many servers and engineers are needed to support Twitch, because that will determine profitability.