There is no such word as “epithany”—nor is it “epifany,” nor “epuphany,” nor any of several other imaginative spellings I’ve seen in manuscripts (and on blogs and Facebook) lately.
Epiphany—as it’s most commonly used in stories and among writers—is when a character experiences a sudden moment of perception, insight or revelation of deeper meaning or direction.
An author might have an epiphany about a character or plot line.
A character might have an epiphany about the meaning of his/her life.
In the case of a character, it should be rare. Limit yourself to one per book.