I’d buy him a gift; something ridiculous, like a sports car, or a European vacation.
But I’d resent him if he bitched that he somehow deserved a share of my winnings. If he did, I’d say “well, you should have bought 2, and given me the next one.”
It seems obvious that any lottery ticket you buy could turn out to be worth millions. If you’re worried that you are giving that windfall away, then don’t give lottery tickets as a gift. I think most people give lottery tickets because it’s only a buck, but it somehow doesn’t seem cheap. Any other gift for a buck would be cheap and tacky. With a lottery ticket, it’s ok, because it could turn out to be huge. If you are going to get the kudos for giving a "good’ gift, then, you have to accept the risks inherent with why it’s a good gift.