Bill Cipher, the big bad of Gravity Falls is a demon who loves spreading chaos and causing people to go insane. Nyarlathotep is a outer god from the works of Lovecraft who has a multitude of forms and avatars. He has similar shape changing, mind warping, and reality bending powers.
They both use trickery and seem to share similar goals, and Nyarlathotep often takes forms inspired by ancient Egyptian lore... when he is not rocking out as Mathew McConaughey to try to destroy some form of tower (allegedly). But Bill's pyramid form seems like a good thematic fit.
Is there any indication that the creator had the intention of Bill being connected to Nyarlathotep?