The above link shows a vintage photo of the original building. Comparing the original with the current location photo on google maps, it seems to me - judging mostly from the masonry sill & lintel of the windows - that much of the original building is still standing there on 6th Avenue.
Yes, so far I think it would be a fair assumption to say that at least the two 'street-wall' sections of the original building art still standing.
I am still not completely sure - but it will be easy to find more. If this is an Historic District, there will be plenty of archival photos & documents: heres hoping this one is landmarked.