I'd imagine he has an impressively comprehensive team around him ensuring he doesn't need to focus on anything other than his work.

That said, working over 14 hours per day 7 days a week is implausible to me. Maybe in short bursts but I doubt he does that for any stretch of time.

The Elon Musk PR machine & cult of public enthusiasm is a massive business asset. When you're in the business of selling dreams to investors and employees pushing themselves to the limit this type of 'fact' is going to get thrown around.