Is Ussop based on Aesop? Aesop was an Ancient Greek fabulist or story teller credited with a number of fables now collectively known as Aesop's Fables. Here is a description of Aesop: 


  "of loathsome aspect... potbellied, misshapen of head, snub-nosed,
  swarthy, dwarfish, bandy-legged, short-armed, squint-eyed,
  liver-lipped—a portentous monstrosity,"


Here are somethings that they have in common. 


They both tell fictitious stories.
They both have liver-lips.
Their names are pronounced the same.


I believe that Ussop might be a combination of Pinocchio and Aesop.
Ussop's name is probably based on "Isoppu" which is the Japanese pronunciation of Aesop. (One Piece Wiki)


The Wiki also claims "uso" means "lie" in Japanese so Ussop is a combination of "liar" and "storyteller" (Aesop). Basically this says it is likley but the source is not at all canon. We don't know as Oda hasn't definitively said, but probably.