ATC personnel have no eyes (Asobo ATC). Sometimes taxi to gate leads to a gate occupied by another plane. Since it is not real life, I wonder what to do, because the sim wants me in that gate, and never mind the excuses. It may have been a long flight and I want the reward of completing the assigned task.

Park in another gate or turn off collisions and park on top of the plane occupying your gate. Not much else you can do.