I'm not sure who 'Robert Arquette' specifically is in 'Pulp Fiction'. There are many characters in the movie, but this name doesn't ring a bell as a well - known character in the context of the film. It could be a minor character or perhaps someone involved behind the scenes in some capacity.
Arquette in 'Pulp Fiction' is an important part of the movie's cast. Patricia Arquette played a key role, and her character added depth and complexity to the story's web of interrelated characters and events.
I don't recall any direct relation between Rosanna Arquette's character and a character named Jody in Pulp Fiction. But it's possible that I missed something.