Elvis influences

Elvis influenced, inspired and copied from these people.

Tony Curtis:- Tony Curtis is successful actor of hollywood, Elvis Presley had told Curtis that he is fan of him, Curtis was so popular in 1940s and 1950s as a screen hunk, Elvis Presley had copied his on-screen hairstyle in 1956. Here is a pic of Tony Curtis and Elvis' hairstyle:-
Pic.
You will find too many differences, maybe both are 100% different but both hairstyles are called as duck tail hairstyle.

Mario Lanza:- He was a fine actor and Gospel singer, Elvis Presley always said that his favorite singer is Mario Lanza and he is influenced by him for Gospel singing.

Other influences:-

Sister Rosetta Thorpe, Roy Acuff, Ernest Tubbs, Ted Daffan, Jimmie Rodgers, Mario Lanza and Bob Wills.

Other stuff:-

James Brown:- He had suggested Cape idea to Elvis.

Jackie Wilson:- He had told him how to dance in the song "Return to Sender".