You usually pay for this sort of thing based on profit, more or less.
In this case, his basis is $0 (his cost to acquire the asset). Were he to sell all of them, his profit is essentially 100%; however, I'm not entirely sure how bitcoin gains are codified. If they're regular capital gains, then it's done around that cost basis ($0 in this case), but if they aren't, then I don't know.
In this case, his basis is $0 (his cost to acquire the asset). Were he to sell all of them, his profit is essentially 100%; however, I'm not entirely sure how bitcoin gains are codified. If they're regular capital gains, then it's done around that cost basis ($0 in this case), but if they aren't, then I don't know.