Hi Gigi
I think Victor put two and two together. He could sense the sexual tension between Gideon and Eva. He knew they had a connection. Eva said herself, he could read situations and people, being a cop. I'm sure he sized up the situation the night Graves and Michna, paid Eva a visit, and wanting to speak to Gideon too.
From Victors point of view, I would say he would thank Gideon for saving his daughters life, after reading the reports, of the numerous rapes, torture and abuse. I would like to think Victor and Gideon had a heart to heart when Gideon asked for her hand in marriage. Of course Gideon wouldn't and couldnt mention the murder, but he could convince Victor how much he loves Eva, and would protect her at all costs.