Bad analogy.
Actually, it was a prety good analogy
gravity is not yet fully observed, and therefore, unproven, and absolutely not a fact.
Say What?
Futhermore, Gdel's incompleteness theorem deducts that there must be observations that do not fit the theory of gravity at all. That is also what Popper clearly states: one day or the other, gravity theory will prove to be false. So, the correct status for gravity theory is necessarily: unproven, false.
Your understanding of the incompleteness theorem seems to be incomplete