Agency - they pay for the ads and manage his accounts. I assume his OF account makes enough money to cover some ads and the benefit (lots of new subs) outweights the cost.
His account has 1600 subscribers on his paid OF account. Assuming 50 % of them are on his 3 USD trial and 50 % are renew subscribers for 30 USD. After OF takes their cut he has roughly 20.000 USD per month JUST from subscriptions. Then add PPV where they scam the guys to buy a few nude pics for 200 USD and you can assume he makes an additional 25.000 USD per month from PPV after OF cut. Of course the agency probably takes 30-50 % of the profit, the rest goes to him.