From Cray:
In terms of mass, yes. Quarters provide for a single crew or passenger on a vehicle. They are not necessarily a single stateroom, though.
The actual mass of the quarters is spread all over the vehicle in many different rooms (depending on the needs of the vehicle, class of quarters, manufacturer's whims, etc.) That mass of quarters addresses needs for 1 person in the ship's laundry, the gym, the cafeteria, the bathrooms, central and emergency air systems, central plumbing, toilets, and water recycling, etc. The actual bedroom might be a private, single-bunk room or part of a multi-person suite. The only constant is the tonnage.
In short, the definition of quarters in BT is about the mass needed for 1 person to get the benefits of steerage, standard, or luxury quarters, but says nothing about how the mass is configured. It could be one room, multiple rooms, or shared rooms.