Through donations and subs
Through donations, advertising revenue and sponsorship.
You can create a donation button or link through various providers. Viewers can then donate money to you via PayPal. Allegedly there are providers where taxes are deducted directly so that you no longer have to worry about it yourself. With this income you have to pay taxes, otherwise it's illegal.
I don't know by heart which providers automatically deduct taxes. (ask google)
If you have made the necessary achievements to become an affiliate, viewers can also subscribe to you. This also gives you money with every subscription.
(Check the "Achievements" tab on Twitch for more information)
In order for you to really make money, you of course need a significant number of viewers, which is not that easy for most.
If you are better known, there are also sponsors who pay you something, but no information about how it works. Probably by promoting them and in return they will give you a certain amount of money to work out. If you are not very well known, you probably have to ask yourself and that must of course also be useful for the OK or make sense so that they agree.
Others gave very good answers. I would just add that you don't have to be tall to get a sponsor. There are platforms like inSTREAMLY where you can be micro-sponsored by various big brands. So sponsorship is no longer reserved for the biggest streamers.
