This feature request is still being reviewed by the feature team.
-WarrenJohn Melendy commented
To clarify, the request is not for a global enable/disable flag for a channel, but for individual users to hide GIFs or disable auto-play of GIFs for a channel when the admin has decided to allow it globally. There does not appear to be an option for this. Currently either everyone has to see GIFs or no-one gets GIFs at all.