Higher FOV means you will render more, so it's a very linear increase in performance impact. Of course it depends a whole lot on what is in the game. For example in a Total War game, the difference between 60 FOV and 110 FOV could mean the game would have to render twice as many units, which obviously has a huge performance impact.
Just so you know how this works:
The first culling step of each frame render is excluding all objects that are either outside the field of view, too far away or too close.
FOV in FPS:s have a bigger impact on performance if it's a game with many enemies and allies, instead of fewer, bigger enemies. For example in a game like Killzone 2 FOV have a big impact on performance. In, lets say 1v1 Unreal multiplayer, not very much at all.