The building has seven floors. The main floor contains reception, a bar, a kitchen, a club, and a green room which leads to the club's stage.
While most buildings in the United States use the North American floor numbering scheme, which counts the ground floor as the first floor, the Empire Arms seems to use the European scheme, where the floor above the ground floor is the "first floor." As such, despite having seven stories, the elevator lists G (ground) and then the numbers 1 through 6.
The "Empire" name is likely a reference to New York, the "Empire State," as all of the suites are named after parts of New York State.
The exterior sign uses the plural "Empire Arms Hotels," suggesting it may be part of a franchise.
The exterior building is extremely tall, but the interior only seems to have seven floors.
Only three floors are accessible: the main floor, plus the fifth and sixth floors.
While it's not always expected that building interiors will necessarily match their exteriors, the Empire Arms' interiors don't match well either: given the arrangement of the elevators in the lobby vs. the elevators on the inhabited floors, the upper floors would be arranged perpendicularly to the ground floor, rotated 90 degrees counter-clockwise to what is expected.
Millennium Biltmore
The exterior of the Empire Arms is based on the Millennium Biltmore Hotel in Los Angeles, which was an early host for the Academy Awards (the Oscars). It's appeared in a large number of TV and films: it was home to Leverage Consulting in the first season of Leverage, and played the part of the Sedgewick Hotel in Ghostbusters.
The hotel is referred to a number of times as simply the "Empire Hotel." Combined with the suites named after New York locations, the hotel may also be a reference to New York's Empire Hotel.
In the base game, the reception computer only listed five suites, and didn't associate floors with them. They were, in order, Albany, Buffalo, Ithaca, Manhattan, and Brooklyn. This implied Boris was on the second floor, although the elevator button needed to reach him was still the 6th floor. The Queens Suite wasn't mentioned at all, although Cuthbert Beckett later mentions Johansen was staying at a suite at the Empire Hotel.
