No talk of passengers, so at the very least one person is missing, but up to 5. Also they have no other submersible that can reach that depth. From an insurance stance, that sounds like a massive liability risk to undertake, not to mention it’s just unwise.
So, in the live feed the BBC has going, there's a post suggesting that a group of explorers were apparently on board based on one of them's Facebook feed, so it's safe to say they probably had the full passenger set on there.
One of the other posts in the feed makes it sound like they only do it a handful of times a year, and that cost is covering a multi-day excursion since they have to wait for conditions to be right. Still, no excuse to not have contingencies, but I think their take gets eaten into a fair bit more than the raw math would suggest.