In my opinion, Faber does not lead Montag to self-realization as much as other characters. I would say that Clarisse McClellan and the old lady who burned herself both play more of a role. So does Millie.
But Faber gives Montag hope that he can achieve self-realization. Without him, who would Montag have turned to for advice about the role of books in the world? Who would have told him that he could escape to the country? So Faber is a help to Montag. He helps Montag in practical terms and he also helps him think about whether books, by themselves, are enough. But I do not think he leads Montag to self realization.
Although Clarisse and the old woman did make him realize but didnt Faber finish what Clarisse and the old woman started by educating him