Had he survived the sinking, do you think Jack and Rose would've remained together?

yes i believe they would have stayed together gotten married and had kids

...I believe so, not only because they have a deep attraction towards each other, but also because I think it's a little hard to separate from someone when you've been through so much together. Yet, in some ways, I see a few disasterly fights. I've read plenty of tagahanga fiction -- either they end up being depicted as a cheesy, super fluffy couple, or they have their good and bad moments in between.