How much can you earn from twitch if you are a gamer?
It depends on a lot of factor, I'm a gamer since forever and even if I don't stream on Twitch because of slow internet connection, I do gameplay recordings especially walkthrough and upload it on Dtube and Youtube.
The most important factor to me is if you are going to be starting this venture, you need to be really patient because you won't earn for a few months and even for years. It takes time to build your audience plus you need to have money too for internet connection, your hardwares, PC, console, headsets, microphones, softwares etc plus the games that you're going to buy to stream. It also depends on what kind of game you stream, famous games like Fortnite who are played by millions are one of the games that has the most subscriber but you also have the most competition there so sticking up with your niche is a great idea when starting.
Second, you have to upload or live stream as often as possible and if you could, do it everyday because the moment you lessen your stream or videos, you would lose subscribers and that's where you earn.
The more subscribers you have, the more money you can earn on Twitch and it also depends, I mean you could earn thousands or you could earn nothing. The gamers that earn a lot on Twitch are the ones who are established, entertaining and definitely has thousands or millions of subscribers.
It's hard but it is worth it if you are enjoying in what you do.
Or there's Dtube, you could earn an upvote from Dtube and you could already earn from your gaming even if you're just starting out.