Welcome to the boards, laurieb! 
First of all, it's very unlikely that multiple principal cast members would be taking their holiday breaks in December. January through March (after the holidays) is generally the most common time for Broadway performers to take the week off, so I wouldn't expect anybody to be out due to vacation. I obviously can't speak to illness or injury.
With regard to Javi specifically, really, nobody can tell ya. He's missed at least the last 15 consecutive performances, some due to preplanned filming/work absences, others due to his illness or injury or whatever. Honestly, he's probably the least reliable performer on Broadway you can expect in terms of attendance, so I wouldn't hold your breath. Sorry!
Either way, for what it's worth as I'm sure you know, the show is the star. It'll be great regardless!