You can see the statistics for top earners at the bottom, obviously they're not all Twitch streamers but I've seen some in the top 10 before and the number is how much they've made as commission.
Why doesn't Twitch have their own donation system so they can take a cut of donations? Basically they need to implement StreamTip. They can then forbid partners (streamers who are allowed to have subs) from having any 3rd party tipping services. It's bad for StreamTip, but the profits for Twitch would be HUGE. There are some streamers, such as Lirik, whose main income from Twitch is probably tips. StreamTip already takes a cut of the tip, so it's not like the streamer would lose money if Twitch had their own tipping service.
This is how a lot of Chinese and Korean streaming services operate. And integrated donation system can allow for more interactive options between streamer and audiences, or even between audiences. (Like streamer present the audiences with two options, and the option that getting more donations will be chosen by the streamer.)
The guy in the first picture, Forsen, is one of the top 5 or 10 Hearthstone streamers in terms of viewers. Depending on his 'competition', I've generally seen his numbers between 5,000 and 10,000 concurrent viewers.
Winter, A guy with 2k viewers for starcraft said he made $70k in the past year. Forsen who is in that picture usually has 17-30k viewers and pushes donations a lot without ever running ads. Honestly i thought he was making more than what is in that picture. I forget what he said the other day. I think he said he was nearing 3k subscribers which would top that number up a lot.
Tbh from watching streams for a few years now, I think the big guys make MUCH more off donations than any ads/subs. Most of the big guys don't even run ads and strictly push donations.
A single guy has donated ~50k to the streamer sodapoppin
This cannot be emphasized enough. Without taking donations into account the predicted revenue is going to be so far off from the truth that it's pretty much useless.
From time to time, a streamer will accidentally show a tab that shows how much he's made. Here's a recent one (I have no idea how big he is):
https://i.imgur.com/OLyQNpk.png
Most of them also make really nice referable money from G2A for each sale:
https://www.g2a.com/goldmine
You can see the statistics for top earners at the bottom, obviously they're not all Twitch streamers but I've seen some in the top 10 before and the number is how much they've made as commission.