Is there anyway i can get my U.S strat to sound like a gibson Johnny smith?

You're never going to get a solid body Fender to sound like a $10,000+ hand carved Gibson.

that said,

you might want to try a Seymour Duncan stacked humbucker, in the neck position.

You can drop one of those in, without modifying the Strat.

Then use that pickup, with some of the treble rolled off, to try to fatten it up a bit

good luck

i dont know alot about Jazz

but im sure if you spent a little bit more money on a new set of pick-ups, that could help.

or maybe your amp settings are a little off

for a bluesy sound..you wanna turn you gain down

treble at about 6

mid at like 0-1

put you bass at about 5 or 6

hope this helps