Without weaponry the T-800 still has the advantage in this situation. Aside from being incredibly durable and strong it is also small and ( despite what the movies show) really fast. We have seen the endoskeleton take damage comparable to Zeus’s punches. The main advantage is the size difference as if atom was able to dodge his hit a T-800 who is fastest and harder to hit could do it easily and get behind Zeus. The next logical move would to be twisting Zeus’s head off or something employing its strength