You could have 10.000.000 Views each Month and still don`t be able to life from it if the biggest Part of it isn`t monetizable. You don`t need to be famous to be able to life from your YouTube Earnings if your Porsche doesn`t need every few Weeks a new set of tires just because you tried to impress that hot Chick from the Gym with a Burnout.
Also since each one of us do have a different Life Standard it`s hard to tell how much you would need to earn to be able to quit your Job. For some $1000 would be already enough while for some others well let`s put it that Way:
Those Tires are damn expensive and the Girl from the Gym does have a Twin Sister...