National Merit Questions Class of 2016

I scored a 230 on my PSAT (80 M, 80 W, 70 CR), but only a 2180 on the SAT (800 M, 700 W, 680 CR). I live in Texas, where the PSAT cutoff score is usually around 220. I take almost all of the AP classes offered at my school, I’m very involved, and my GPA is a 4.0 unweighted. How much will my SAT score hurt my chances for a National Merit Scholarship?
Also, how much will NMSF help for college admission at prestigious schools that aren’t sponsors, such as Harvard or Stanford?
Am I guaranteed admission at schools that do sponsor NM?

“How much will my SAT score hurt my chances for a National Merit Scholarship?”
It wont. Just be sure you get the NMSF forms from your guidance counselor in the Fall of your Sr year and fill them out, including the essay.

“how much will NMSF help for college admission at prestigious schools that aren’t sponsors, such as Harvard or Stanford?”
virtually none, as most of the other 15000+ NMSF usually end up applying to top colleges as well.

"Am I guaranteed admission at schools that do sponsor NM? "
no.

National Merit status is based off your PSAT score, not SAT score so you should not have an issue. If you are a National Merit Semifinalist (which is sounds like you will be!), I know you will be guaranteed admission into the University of Nevada, Las Vegas. Semifinalists are guaranteed admission and students that are finalists receive the President’s Scholarship, which covers full cost of attendance and a semester of study abroad.

Good luck with your senior year!