Oh, he knows. He tracked the three to the safe house and when Valentin told him off one too many times, Victor had one of his goons shoot Anna. She's currently recovering in the hospital with Val by her side, of course, which is why Ned is suddenly so upset about ELQ not having leadership. The writers did not really care about ELQ's lack of leadership during the 6-8 weeks when Val was presumed dead. Ned apparently stepped in to run it, and just because Val turned up alive, Ned did not have to give the CEO job back to him, but apparently did. Very sloppy. But like I said, Victor did find out his son and the others were alive. They're saying that Victor just wants to kill off 50% of the population of Earth in order to save the planet (Thanos?), which is ridiculous since Victor has never struck me as an eco-warrior of any sort. I cross my fingers and hope he's lying to Spencer, Trina, and Liesl and has a much more selfish motive for all this, but it might actually be all they're going to write.
They're not heading to Cassadine Island, actually. It appears that this bunker they're trying to find is on an island off the coast of Venezuela. The coordinates for the bunker were etched onto the Ice Princess necklace, and apparently Victor stole the Haunted Star to sail there rather than...oh, I dunno, FLY there on a private jet? The idea that the boat could get from Western NY to Venezuela in a few days is preposterous, too. The locks on the St. Lawrence Seaway alone would take the better part of a day to navigate, and they'd be sailing against the Gulf Stream to head south. For realism (remember that?) they could just as easily said the bunker was on an island off the coast of Nova Scotia, since it really doesn't matter where they're going. I guess (??) he plans to release the biotoxin from the bunker, so you'd think he'd be some place more centrally located; perhaps they're afraid there might be too many comparisions to the lab leak in Wuhan, so they sent Vic and the gang to someplace that would be the polar opposite of urbanized China.