THIS IS NOT AN EXIT

"The entrance says EXIT. There isn't an exit."

Tim's post on Maya Deren and meshes made me revisit this line from the telling of JvD's last party night. I remember talking about this during book club, but this line made me think of the ending of Bret Easton Ellis' American Psycho. As noted in the wikipedia for AP:

"The incipit of the book has Bateman staring at a graffiti on a Chemical Bank building, reading Abandon all hope ye who enter here; this phrase appears over the gates of hell in the Divine Comedy. The book ends with a scene similar to its beginning, as Bateman sits in a bar, staring at a sign that reads "THIS IS NOT AN EXIT" ; a reference to Jean-Paul Sartre's play No Exit. The opening and closing phrases summarize Bateman's life as a living hell he cannot escape."

Is DFW referencing Sartre or Ellis? or Both? or Neither? It seems as likely any of the three.