Recently JC Penney moved into most of the Manhattan Mall and they are doing construction on the lower level, which is visible in the corridor between the subway and PATH trains. It looks like at one point you could enter Korvettes directly from the station. At some point, presumably the store's closing in 1980, that entrance was sealed up but the renovations reveal both the sign and the stairway leading from the subway into what was the store.
This was not listed on any of the several NYC blogs that usually post this material. I gave Esther Crain of Ephemeral New York a heads-up about the sign and she put a nice write-up on Korvettes on her blog.
Longer view where you can see the stairway and where it was bricked over.
Close-up view of the Korvettes sign (there is a reflection of the corridor in the glass window).