This isn't such a great idea, honestly. I've heard from a pretty popular gamer (ImAnderZEL, just under 100k subscribers at the moment) that even though he can't give official numbers or anything, he makes just about/less than a standard worker at McDonalds. You probably could live paycheck to paycheck working as a full time commentator/entertainer/producer, but the chances of you reaching that goal are quite low, you'd probably have to get a job to support yourself while you are a 'hidden gem', and when you do reach a point where 'hey, the monthly paycheck I'm getting from my YT channel(s) are able to support me", the job you currently have probably supports you better.
I don't claim to be an expert, but I need to stress: Do not start putting up videos with the sole thought of making money and living off of it. the YouTube community, from what I've seen of it, quite dislikes 'money whores', and you'll suddenly find your audience, well, smaller or completely gone. Only do it if you enjoy doing it, and if you have the ability to support yourself, should the YouTube idea not work out for you.