Forks, Washington is a real town (Clallam County, pop. ~3,500), but the Forks depicted in Stephenie Meyer's Twilight series is a fictionalized version. The books describe it as a tiny, perpetually rainy logging town; no official census exists for the fictional portrayal.
If you're asking about the real Forks, the 2020 U.S. Census recorded 3,532 residents. The Twilight tourism boom has boosted the local economy but not dramatically changed the population.