I would say 1.
In 2012 SVB made $147,923 in tournament pool winnings. He is sponsored and as such he likely keeps most if not all of that, and has added revenue from TAR matches, gambling, ect...
The next Americans on the list are under $40,000 in earnings, they do not have the sponsorship advantages of SVB and even if they did and they got every bit of their $30,000 and change in winnings (before taxes) that is hardly making a living in anything.
How many pros actually make enough money "playing pool" to afford their own rent instead of living on their friends couch or bumming a spare room? How many can afford to pay their own food bills regularily, how many can afford to go play in tournaments on their own dollar without coming to AZB and asking people to pay their way? How many make enough money playing pool rather then working in a pool hall giving lessons, occasionally working behind the bar, and running the weekly tournaments?
There is 1 pool player making an actual living playing pool in the USA and that is SVB. Johnny Archer might make a living from pool, but he does not make it as a professional winning his earnings, he makes it selling cues with his name attached to them. He grossed just over $27,000 last year in pool winnings, I need to net that after taxes every 6 months just to cover my bills. There is no living there, especially with a wife, kids, a mortgage, ect...