>Does he understand that the universe has an end and that immortality for that reason is an impossible goal to achieve?

I think he understands that this is a useless correction, and that e.g. 1,000,000 years of life are both very much below the heat death of the universe, and close enough to immortality compared to our 80-90 year life expectancy, for the issue not to matter.

That said, he's going nowhere near even double life expectancy, just like everybody else wont go there in the next 100-200 years (my prediction, would bet on it if only we could see the result of the bet). Not only we won't be getting that, but we'd be lucky if we avoid worsen quality of life and career prospects, and premature death due to climate change, wars, famines, and so on.