Other outfits can probably injure Twitch by poaching key stars, but it's not a path to success for these rival services. The absolute most they can achieve is kill off Twitch, at which point it's as likely the piles of small creators just do Youtube, rather than figuring out tooling and financials for your new live service instead.
And if your plan is "Aha, we'll kill Youtube too" well you'd better be loaded for bear 'cos that platform is not messing around and the people behind it aren't going to run out of money any time soon.
Microsoft tried with Mixer, they poached some Twitch stars and shutdown earlier this year. those stars just returned to Twitch.
https://www.bloomberg.com/news/articles/2020-10-07/microsoft...
We'll see what happens after the impending antitrust litigation I suppose.
Youtube is riding the long tail with ads. Hardly anyone watches past VODs on Twitch.