Given that she now represents all of New York, not just a pro-gun upstate district, I expect to see her support for gun rights soften. She'll need to win a lot of votes from NYC to get re-elected, so it will surprise me if she sticks to her pro-gun views.
It will be particularly interesting to see what Chucky Schumer does in 2 years when Gillibrand is up for re-election. Rep. Carolyn McCarthy is extremely anti-gun and has said she will challenge Gillibrand for re-election. If McCarthy does run, will Schumer support Gillibrand or McCarthy?