I know a little bit It's not much but I hope it helps.

there's a pool of voting power each day and the more steem power you have the more you can take from that pool to vote on other people posts. Whales generally take most of the vote pool but theoretically if I understand this right, if you were the only one to vote that day on the entire steemit platform you're votes would pay out thousands of dollars.

so voting power is based on steem power plus everyone else that is sucking down the voting pool.