Gobekli Tepe isn't some 'lost' civilisation, it's just old,
very basic but technically urban architecture.
Here
It revised the time scale of when we think humans began settling into relatively 'permanent' dwellings with such advanced technology as walls and standing stones, and invites questions as to how widespread such a level of development may have been - whether it's just a regional thing or could be expected further throughout human colonisation at the time. But it doesn't make Atlantis a thing. Meanwhile the dating of the Sphinx is an issue of how we don't have direct evidence of such, and instead must work with written references for what ruler it's associated with, and the typology of the building style. Many do believe it is older still than the 4500-ish mark currently given to it, whether for conspiratorial 'It comes from a civilization before Egypt!' musings or not generally accepted but technically possible theories like the erosion on the enclosure wall being water derived (whether or not it is, or if such actually implies an older date, subject to debate) meaning the Sphinx must be pre-desertification, and thus, far older than believed right now.
