The phrase, "I do not know if gods exist or not" is a complex modal claim that can be modeled through epistemic logic. It is not a tautology. The proposition, "Gods exist or not" is a tautology.
But the real problem is not one of tautology, it is one of concept formation. What are the proper referents of gods? are they found in percepts or higher order concepts? Are they mere fantasy? If the latter, then we should be igtheists, which, if I am not mistaken, no one has considered as a plausible position. Atheism and theism? Pfft. Both take too much for granted. Think about the concepts employed, and then come back.
Hope this helps.