The data I have shows a marriage to Mary Pugh in 1748 and death in 1790 in Randolph County, North Carolina. I don't have any information on how he got to the US or the date he immigrated. There was an unsubstantiated reference to him coming to the US (Pennsylvania) in 1747, but I could never confirm this.
John Frazier and Mary Falconer show up frequently as "possible" parents of George Thomas, but I have never been able to substantialte the connection and go any further back with the connection. The only reference I have found regarding John/Mary did not show George Thomas as a son.