When Jack and Rose go down to having dinner for the grandstaircase, the boy who this behind of Rose is Jack Thayer and to his side this his father
Where is the deleted scene from? You may well be right.
Jack Thayer appears in, at least, two made-for-TV movies: SOS Titanic (1979), and the 2012 miniseries "Titanic." He's played by Nicholas Young (he is mentioned, but uncredited) in the former and Ryan Hawley in the latter.