I mean, I would say that it is, but honestly I don't think I'd do it. Taxi's are plentiful and pretty reasonably priced from the train station to this property. We were there last year and I don't remember exactly what we paid but I thought it was reasonable for sure (its a pretty short trip). If walking, you'll be dodging lots of tourists, etc.

Honestly, if staying at IL Tornabuoni, the taxi fare will be an infinitesimal (not even noticeable) percentage of your Florence trip.

But could you walk it, sure absolutely.

Regards