Zakat On Sahib-e Nisab Savings Collected From Zakaat Money
I’m assuming that he was collecting money as a charity to spend on others. If that’s the case then he doesn’t owe any zakat on the collected money. Nisab is for personal savings / assets only. If he was collecting the money for himself and his family and now has savings beyond nisab then yes he will have to pay zakat on his savings and he’s not eligible for zakat anymore.