Their is no evidence to suggest what he says is true. You are asking people to believe in santa claus, essentially. Any of a number of things could be evidence. It just so happens that there is indeed something on this planet that proves there had to be such a civilization. Its now been proven that the Egyptologists are either hiding something or just dont know what they are talking about.
Proof is a big word in science.
This has been proven by geologists from Oxford and Boston university. Not only that,but its highly doubtfull that the Sphinx was originally carved with a mans head on it. But whatever the case may be,that face on it now is not king Chephren like the Egyptologists tell us it is. There's that nasty word again. Personally, I think you have been watching the sci-fi channel for too long.