Is a person's pledge to give a monthly sum of money to his niece for life, which continued for years and then ceased due to people's instigation, considered a gift or maintaining kinship ties, and what is the legal ruling on this cessation that harmed her?

Mere intention does not obligate the monthly payment of the financial amount. It is advised not to be influenced by backbiting and to reinstate what was being given to the girl, hoping for Allah's forgiveness, because showing kindness to her is a remedy for what occurred between them due to backbiting. What was being given to the girl could be a gift, an act of maintaining kinship ties, or charity, and charity given to a relative is both charity and an act of maintaining kinship ties.