This is a massive project, and while it could definitely be possible to do. You might want to try appealing to the more casual Minecraft player, rather than users of Bitcoin. I don't know what the demographic would be for Bitcoiners that also play Minecraft. Instead, you should try promoting it as a way of earning money while playing Minecraft. That would likely appeal to the general public more, and therefore you would generate more players.
A partnership with a gambling site that has an API? Possibly allow users to bet on the site while in-game or (with the help of the Minecraft plugin) make bets more fun. Income would then be collected either directly in a fixed payment from the site or a % commission.[/li][/list]
This is something that is probably more hassle than its worth. Depending on your country of residence, you would likely have to register with a gambling commission, get licensed, and wouldn't be able to accept users from certain countries unless you have a sufficient enough license.
I understand you wouldn't be providing the services exactly, and just using an API. However, I do still believe that would require being licensed.