It depends on the use of the mezzanine space.
Yes, if the mezzanine is providing additional floor area for the property use, which would not be possible without the mezzanine. For example, in the example below the mezzanine is providing additional office work spaces. In a theater, the mezzanine provides additional seating.
No, if the mezzanine is not providing additional floor for the property use. For example, in the photos below, both warehouses are using the same amount of vertical space. The warehouse in the second photo has easier access to their goods on the upper levels, but they do not have additional warehouse gross floor area.