It all depends on how you count. DA2 page shows 9 companions, but ... if you don't count the DLC companions (Sebastian, Tallis) DA2 only has 8. (If you do, it has 10).
Also, as you can never (at least after the intro) have both Bethany and Carver (them being mutually exclusive), technically there's really only 7. After Act I, where you're pretty much assured to have Bethany or Carver gone, somehow (until their possible Act 3 reappearance), there's only 6.
If you count Loghain as the "secret companion," DAO has 10 companions. If you don't count him (as most don't recruit him, and he's only available at the end, anyway), and don't count Shale (who's DLC), then there's only 8. Some don't count Dog as he's not a humanoid/sentient, so then there's only 7. (We'll also ignore the redshirts like Jory and Daveth.)
I guess the familiar claim that "both DAO and DA2 had 9 companions" depends on how you count.
So I tend to wonder if the claim that there will be 9 means there will, in fact be 9 at launch, and a 10th as DLC ... etc, etc.