Since Dr. Faustus was written by Marlowe in a heavily Christian age, though the story was taken from earlier chapbooks, he intends for the emphasis to lie with a discussion of free will instead of with a discussion of the pagan religion idea of a conquering and governing Fate. This is especially true since the Protestant Reformation, in which free will plays such a prominent theological role, was a prevalent social topic and concern. Therefore, within the context of the drama, Dr. Faustus, the fall and fateful end of Dr. Faustus is seen as the result of his ill-judged exercise of his free will, which leads to one of the themes of the play: the power and role of free will.
I believe Doctor Faustus to be a victim of free will rather than fate considering he had numerous opportunities to repent and to leave the path that led him to ruin and eternal damnation. Only because of his persistence in the choices he made does he end in hell.
Also, he was the one who called Lucifer on his own account because of his desire to rule and his pride. Faustus saw himself as intellectually superior individual who should therefore have divine powers. His pride has not left him and together with his other weaknesses (fear of death and pain) stopped him from asking God's forgiveness and mercy.