CPC (cost per click) is what an affiliate pays an ad network for one click. In betting affiliate marketing it is a cost, not a commission model: programmes pay per player or on revenue.
Example. CPC is 0.20 EUR and click to FTD conversion is 2%. One FTD takes 50 clicks, that is 10 EUR. If the programme pays a 40 EUR CPA, the campaign earns 30 EUR per FTD.
Gambling advertising is restricted by law and by ad network rules. Before buying traffic, check what the network allows and what the programme forbids, for example bidding on the brand name.