No gift option under share icon

There isn't a setting, giftable items should automatically show the option. What are you trying to gift - you can't gift free items, nor things such as season passes.

As you refer to 'share icon' I assume that you are trying to do it from an iOS device (and the film has been released, it's not a pre-order ?), if you do then this is what I see on my iPad (iOS 9.0.2) for a film :