http://www.techradar.com/news/game-gifting-is-coming-to-the-xbox-one-store

Update: As promised, game gifting has arrived on the Xbox Store for members of the Xbox Insider Program. As a result, it's now possible to purchase an Xbox One title and send it directly to one of your Xbox Live friends or to an email address. Once they've received the game, the gift recipient only has to redeem a code to download and play it. 

It's not clear if this is exactly how the feature will work when it's eventually rolled out to the wider public, but it does seem likely. We'll update when the feature leaves the Xbox Insider Program and becomes more widely available.