Unless there have been zero births since this article was published, even if you take the 50,000 death estimate from Hamas at face value, the population has increased since the start of the war. Of course, there is reason to suspect the Hamas figures, since they have been systematically manipulated, don't distinguish combatant deaths, don't separate out deaths from natural causes, and don't call out deaths caused by misfired Palestinian rockets.
The central camps have been almost totally untouched since the hostages are being kept there: https://www.jpost.com/israel-hamas-war/article-804993 (article is a few months old but this is still true). And even outside of these camps, 16+ hospitals remain operational in Gaza despite serving as terror HQ.