So the streamer is being abused?
Who knows.
She could very well be.
She could be lying.
They could be doing some "advertisement on domestic abuse". Etc.
Domestic abuse claims are, more often than not, really fucking hard to prove because it usually becomes a "he said / she said" situation.
There's this tendency on the internet to use "famous" fake claims, like the episodes with Depp, or Neymar, and use them as an every day parameter.
Which makes this way more complicated.
Even if it can't be proved, but she's indeed in an abusive relationship, best thing would be to cut ties with him, but, once again more often than not, it's never that simple.
From a legal standpoint, the stream she did, in which is shown him screaming and gaslighting her, can easily be turned into "she manipulated him into an angry frenzy and tried to paint him as violent, when that was an abnormal situation". That could be his lawyer argument. Bring a bunch of people saying "he's very well loved by the community" or whatever and suddenly "there's no way this good fellow could do such a thing if she didn't provoke him to do it".
People here can cry and scream as much as they want, doesn't change the reality of what happens in court.