I'm 99% certain that Fisher's ascendancy did result in a large increase in USCF membership during the period 1970-1975. Less certain though if that extended into, or throughout the 1980's. But if you were to compare USCF membership numbers in the early 1980's to those in the late 1980's I believe they would show a decreasing trend. This is based on my understanding of information relating to this that I have encountered over the years, but I don't have the "official" data at hand to prove it definitively.
Check the sentence in the second paragraph of the History section of the USCF Wikipedia article.....i.e.,
"Membership experienced consistent, modest growth until 1958, when Bobby Fischer won the U.S. Championship at the age of 14. This began the "Fischer era", during which USCF membership grew thirty-fold, to approximately 60,000 in 1974, after Fischer had won the World Chess Championship."
https://en.wikipedia.org/wiki/United_States_Chess_Federation
Otherwise you might contact the USCF (US Chess) directly......
From the USCF website:
FAQ's related to US Chess:
Q: How do I contact US Chess?
A: Email us at: Contact Us or use our Staff Directory.
Q: How can I get information for a membership and a free copy of Chess Life?
A: Call our office at 800-903-8723 X4 Monday-Friday 8am-5pm Central time; email us at tlee@uschess.org; write to us at US Chess, PO Box 3967, Crossville, TN 38557; or fax us at 931-787-1200. Include your name and address and we will gladly send you a sample magazine and membership details.
We all know that Booby Fischer, especially with his WC match, inspired a chess renaissance in the USA.
For the sake of argument, I'll put this surge between 1970-1975.
I'm trying to determine if these was a large increase in USCF membership during those years and, if there was (which seems reasonable to just assume), did that increase in membership extend into the 1980s or did it quickly fizzle out?