This is a civil case, not a criminal trial. I'm pretty sure there is no requirement for a unanimous ruling in a civil trial.
Waiving his right to a jury trial in New York City was almost certainly the right move.
I was slightly mistaken, most states do require a unanimous verdict for civil trials, in NY State they do require unanimous vote, they require a 5/6ths verdict, meaning 2 of 12 in a jury trial, so in this case Trump would need to convince 2 people.