the Doctor says, "Someone was trying to build a TARDIS".
He calls it an alien timeship, and it apparently worked, traveling via the Time Vortex and all that before it crashed.
On the other hand, it wasn't grown by the Time Lords, it's not dimensionally transcendental ("bigger on the inside"), it's built for 4 pilots instead of 6, it seems to have a computer AI instead of being alive, it doesn't have Gallifreyan writing all over, its interior is somewhat spartan, and its default shape when not cloaked is some kind of 4-legged metal spidery thing rather than a featureless white box.
So, does that count as a TARDIS? It depends on your definition. In the strict sense, no, it's not, in the same way a Toyota isn't a Ford. In the more general sense (which the Doctor has used before, when describing the DARDIS as a "Dalek TARDIS"), it is, in the same way a Toyota is a car.