The timing belt cover does not seal oil as the belt is not a lubricated part. The leak is most likely the front crank seal if it is low or the cam seal if it is high.
You really need to take this to the dealer to have the p/s system tested with a pressure tester to determine if it's the pump or the steering gear; it could be either. Otherwise you can only "throw" parts at it. I'm assuming the fluid level is OK?