The margin of error is 6 points. The only thing a bigger N will do is reduce that MoE.
You can see where it is settling.
I understand the skepticism but still after her Instagram went up 65k people registered to vote within 24hrs nationwide. It's also true that more people tend to sign up before the deadline, but I think her message really had an impact.
In Tennessee where Swift is registered to vote, also saw a large spike in sign-ups. "Vote.org, told BuzzFeed that the organization had seen 2,144 new registrations in the last 36 hours, and 5,183 so far this month. Those numbers far outstrip the 2,811 Tennessee new voters who signed up during the entire month of September"