Both of these numbers pale in comparison to the civilian losses of Germany in WWII, and the Allies are not generally considered to have performed a genocide.
Clearly the absolute number of casualties (not even civilian casualties in this case, that is allegedly more like 15k) is not sufficient on its own to define a genocide.
The raw number of people killed isn't indicative of a genocide, it's intent and actions against a specific population. Over 1.5 million (out of 2 million) Gaza residents are displaced and facing starvation. Almost all of the hospitals in Gaza have been destroyed. Many would say Israel is committing genocide and the court today said they will continue the investigation because it's plausible.