I don't think that she's sitting on a mirrored floor but it got me thinking how a mirrored floor would make this photoshoot look even cooler.
To make a mirrored floor for your studio that wouldn't break when you stepped on it you can buy mirrored plexiglass from the Home Depot in sizes of 36" x 42" for $74 and 36" x 48" for $84.
But the cheapest way to go might be to buy plexiglass from Lowes and mirrored wrapping paper from the dollar store. Lowes plexiglass comes in a very large size of 36" x 72" for only $55. Place the wrapping paper on the floor face up then place the plexiglass on top of the wrapping paper.
And does anyone know where this image came from? Searched and searched to no avail.