I'm a big proponent of streaming being basically a marketing tool for content creators, rather than relying on direct income from streaming as a regular income source. At high levels like where Ninja is, you can make a significant amount of money through streaming alone and off of deals like he made with Microsoft, but even he has sponsorships and makes money that way.
That said, the advice I give to my content creator friends who are serious about creating content as a moneymaking venture is to create a small business that makes money and use the content they create to advertise for that business, similarly to how MatPat has a sponsorship from Audible and integrates their advertising into his videos. For example: I host an anime podcast and I run an anime figure store, so I make sure to mention my anime figure store's website at the end of every episode of the podcast. That way I'm not beholden to anyone else in order to profit off of my content.
Artists have it even easier, since they're already in business if they're taking commisions. If an artist streams regularly on Picarto, or posts things like speedpaints to Youtube, they should make sure to deliberately mention that they take commissions and let people know where to find more info.