Format of the conversation matters. What I saw was a friendly matching of wits, in which of course your father wants to win. If you seriously want to change his mind you may need to have a heart-to-heart -- more like "Dad, I'm worried about you. I want you to understand why I don't want to die, and I don't want you to die." That's a harder conversation to have, and it's a risk, so I'm not out-and-out recommending it; but I don't think it'll sink in that this is serious until he realizes that this is about protecting life.

The counter-arguments here are good, but they stay pretty much in the world of philosophy hypotheticals. In addition to laying it all out cleanly, you may want to say some things that change the framing: compare cryonics to vaccination, say, a lifesaving procedure that was very slow to catch on because it was once actually risky and people took frequent illnesses for granted. Or, cryonics is a bet on the future; it's sad that you would bet against it. If he hasn't seen "You only live twice" show him that. It's not misleading; it actually aids understanding.

The pizza thing you wrote is accurate but it's not how I would put it; it's a step in the direction of abstraction which makes it harder to actually change your mind. I'd use, as a simile, something like people dying of smallpox. I don't want people to die of smallpox, even though the universe doesn't give a damn whether humans live or die, even though there's some parallel universe where smallpox doesn't exist. We're here and we give a damn. We want less death, less destruction of human minds and identities.