Leighton is the only way I have seen it spelled and pronounced the way you want it pronounced. Tjough Layton may be a correct way of spelling, it just looks odd, IMO
My daughter's name is Leighton Noelle, but I have a friend who named her son Layton Rhett. I think the latter is more masculine, and the former is more commonly used for girls.
Re: Layton vs. Leighton for a boy