If I get someone an iTunes gift card, can they use it to buy movies and then watch those movies on AppleTV?

I haven't really been able to find a practical answer on any Apple site or forum. My brother buys & rents a lot of movies via his AppleTV. I want to get him an iTunes gift card but am not sure if buying movies on the AppleTV works through iTunes. Would an iTunes gift card work for this purpose? I know it may have to be redeemed on a phone/computer but I want to know if it can then be used on the AppleTV.

Yes. They can load the value of the iTunes card into their Apple account, then they can use the value to get anything they want, at least anything available via iTunes.

I've been an Apple customer/user for many years. I've had the value of gift cards used to pay for music & HBO Now subscription and movies.

Yes the gift card would work.