Excerpt from Scientific American article.
"The Titan is a battery-operated watercraft. Given it has lost all contact with its surface vessel, it may have suffered a power failure. Ideally, there would be an emergency backup power source (such as an independent battery) to maintain emergency and life support equipment – but it’s unclear if the missing vessel had any power backup on hand."
Given that nobody at Titan could tell you, I guess that's a big no. These poor fuckers are toast. I guess the CEO on board is no longer proud of saving a few bucks on back ups.