to help someone to work or operate normally through a difficult period, usually by lending them money

Can you lend me some money to tide me over till the weekend? 你能借我些钱帮我撑到周末吗？

Have another piece of cake. It'll tide you over till supper. 再吃块蛋糕吧，这样你就可以坚持到吃晚饭。