I think he does though because he seems to know legal issues and so on and he has been able to blend in. He knows how to drive a car. He knows about money. I think there must be something there. Like Jefferson said about the two worlds waring with him. He knew about the civil war and to call Emma’s car a bug.
I think that Gold remembered when he met Emma and heard her name in Granny’s Inn. I think that was the loophole. That was why he was so desperate to know Snow’s child’s name.That doesn’t explain how he found Henry for Regina though and i agree that was always the biggest evidence that he knows, but there could be another explanation and i really hope that there is.