According to this website, yes indeed, the King was a nice Jewish boy. His maternal line can be traced to Martha Tacket, a Jewish woman. Elvis' beloved mother, Gladys, taught son Elvis all about his Jewish heritage and Elvis was a student of Judaism and Kabballah long before it became fashionable in Hollywood. He wore a "Chai" pendant and even had a Star of David engraved on his mother's headstone.
Elvis wearing the "Chai" onstage.