Gatekeeper is strongest when it was rezzed this turn, so it would combo with cards that allow you to derez your own. Cards that help you get more activations from the rez strength ability are needed to help combo.
Blue Sun: Powering the Future to replace this where needed, with another strength boost. (Thanks blackcherries)
The Foundry: Refining the Process can fire and get you more of these, with the help of other cards below.
Divert Power makes something cheaper while you get to trigger this rez strength again.
Test Ground allows you to fire the trash ability, derez Gatekeeper, and then re-rez Gatekeeper with unexpected strength.
Other combos, provided you were using them already
Plus, Gatekeeper is cheap and might give you some recursion of used cards if you can catch the runner flat.
Is it for every deck? No. But it might have a place in some.
(Edited to remove bioroid research reference and added blue sun)