In the final battle infront of the Gates of Aren around 400 soldiers of the 7th Army were still fighting and died infront of the city. Afterwards 10.000 Malazan soldiers got crucified, which gives us a very good overview of the Malaz casualisites. The casualities during the whole chain of dogs are difficult to esitmates, because we don't know how many soldiers the 7th Army had at the beginning. A Malazan army normally would have around 10.000 soldiers, but at the time of the uprising, few armies were in full strength. On the other hand more Malazan units joined the army on the march, like the Hissar Guard and the Sialk Marines. So the Malazans probably lost around 20.000 soldiers.

The civilian casualities were higher, as around 20.000 refugies died during the crossing of the Vathar. Maybe 30.000 casualties overall with another 30.000 reaching Aren.

I don't think that we can make any good guesses about the rebell losses. But they were significant for tribes like the Semk and the Tithan, and several rebell armies were destroyed or decimated.