I'm not sure how large a 9x9 tent is, so it's hard to say. I have a Seek Outside Tipi with a stove. Without a stove it can easily sleep 3 people with gear, and 4 people with very little gear. With a stove it can sleep two people with gear.
I'm guessing my tipi is probably a bit bigger. But Dave's advice sounds sound.
One thing about these stoves is that they burn out pretty fast.
What i want to do is to buy or make (most likely buy because cuben is so dang expensive and i don't want to mess it up) a large cuben pyramid tent, and line it with an IR reflective liner (like heet sheets, but hopefully something more durable if i can find it and it doesn't weight too much).
Will do a few things, create a double wall so condensation is less of an issue when not using the stove, creates a still layer of air in between walls increasing insulation some, helps to protect the cuben from any potential radiative heat damage, and then the reflective liner maximizes warmth through reflection of the heat back to you. The latter means i could use less fuel at a time and tend to it less, or so i'm hoping :/