The equipment and methodology can vary greatly from one real estate shooter to the next.

Some use the Canon 11-24 on FF, many use the Nikon 14-24 also on FF. The Canon 14mm/2.8 is another one. The 10, 11, or 12-whatever lenses and even the Sigma 8-16mm lenses on APS-C are also popular. These are all rectilinear lenses.

Then there are the photographers that do pan and stitch either with a conventional lens or with the shift movements of a Tilt/Shift or Perspective control lens. Since a lot of that is also exposure bracketed for HDR/exposure fusion, your sample image could be a composite of as many a 4x3 grid with anywhere from 3 to 5 to 7 bracketed shots at each position. Such time consuming work is usually only done for very high end properties.

On the other end of the scale, since many real estate clients don't require very high resolution, compact cameras, which make large depth of field easier, are also popular. These can be something like Micro Four-Thirds interchangeable lens cameras or even a fixed lens compact with a very wide angle of view.

There are a few specialized cameras designed particularly to be used for real estate interiors. The Matterport system uses a series of scans with a specialized 2D/3D camera to build a very detailed 3D model of a space from which virtual tours and 2D views can be generated.