This essay explores the possible influences of Gorgias' thought on Socrates as represented in Plato's Apology. "No one sins willingly" is a theme both of Gorgias' work and of Socrates, for a start.
Calogero, Guido, "Gorgias and the Socratic Principle Nemo Sua Sponte Peccat" (1955). The Society for Ancient Greek Philosophy Newsletter. 7.