Do Victor and the monster become more similar as the novel Frankenstein goes on?

Absolutely! As Victor self-alienates himself because of his fear of the creature/monster he creates coupled with his guilt for having abandoned him, he becomes just as much a social outcast as the monster, who is shunned by all due to his hideous appearance.  In addition, the creature feels he is justified for his wrong-goings in the same way that Victor feels justified in denying blame for the actions of the creature.  Being the creature's father, Victor has a duty to accept and protect him; by neglecting this responsiblity, he indirectly causes the murders and may be looked at as a murderer himself.  The creature, regardless of how "wronged" he has been does not have the right to murder.  They almost become one and the same, at least psychologically.