The reality of streaming is a constant uphill struggle. You have to excel not at the game but at being a broadcaster- there are so very many all vying for the same audience. I have spent a lot of time on Twitch, streamed for a long time before a move forced me to stop. Good friends with lots of streamers and the behind the scenes reality is harsh. It's seeing others doing the same thing but a lucky break making them incredibly popular, it's counting viewer and sub numbers knowing at any point it can drop below the needed income.
I've seen popular partnered streamers miss trends, fall behind and have to get real jobs. Is she a partner? There is no way at all of making a living at streaming without being a partner on Twitch or the equivalent on other platforms such as Mixer. Youtube income is very hit and miss, so many rules to follow and many Youtubers suffering with demonitisation and just really poor management.
She also needs to be prepared for the utter nonsense female streamers have to deal with. I've never streamed with a cam, so no one sees me just the game and me talking, yet I still had to deal with misogynistic and sexual comments and messages. Obviously anyone on the internet is open to that but in streaming it seems a lot worse. I moderate plenty of streamers on Twitch (basically stay in chat and delete certain messages, time-out and ban viewers according to the rules of Twitch and the streamer) and I've seen all kinds of vile things. Most streamers are used to it, brush it off, carry on but behind the scenes even the most experienced streamers can find it very tough. Constantly being told you are playing wrong, bad at certain things, picked the wrong weapon.... it does get to you. As long as she is aware of that aspect and feels like she can handle it.
I have a friend on Twitch who is a full time streamer and last year bought a house from his income. It is possible to 'make it'. But as a mod I've seen him struggle with numbers, sub counts, toxic chat, worry about changing game, worry about who to play with for the best stream and the best exposure. He routinely streams 11-12 hours a day, 6-7 days a week, and suffers a lot of sub drop-off if he even misses a few days. A short trip to visit family means no stream, no visibility, no new subs and loss of income. I've also seen relationships fall apart due to the amount of time spent building the stream and the brand.
It's tough, it's public, and it definitely isn't not working- it's very hard work! You are selling yourself just as much as a TV presenter or actor but all the work is your own, sorting self-employment, organising brand deals and sponsorships, even the amount of work put into the look of the stream, the emotes, alerts and the music you play. I'd highly recommend she goes into as many streams as possible, in lots of directories too, see how people have set them up from the info under the stream to the chatbots used. Think about what happens when this game isn't the hot new thing and audiences move on, follow lots of streamers on Twitter to see how they conduct themselves and sell themselves.
There is a lot of fun to be had but it is a tough business!