During the expert planning of mission Flooding Out Al-Aqsa, there were probably estimates not only of how many Israelis could be killed, but also how many Gazans would die as well.
The Gazans managed to achieve an extremely high kills-per-day rate during the first 24 hours of the war. Even after taking into account the Israelis that died from IDF friendly-fire; the Gazans still managed to kill 1100 Israelis.
Perhaps the Gazan commanders themselves did not expect that kill rate efficiency. So for the Gazan jihadis, and their supporters, day one of the war was a tremendous success.
But as we know, rarely does a war last only one day, so each day that follows, the numbers start to change. The Gazan kills-per-day rates of Israelis continued to drop as the war evolved.
On the other hand, the IDF, chose a different approach, and had much lower kills-per-day rate of Gazans. The IDF preferring to have a more paced rate at the war, instead of an all-out attack, resulted in kill rates much lower. Of course, after seventeen months of war, the total-kill-counts continue to rise for both Gazans and Israelis.