to continue living after a point at which you might easily have died

Since his cancer was diagnosed, he feels as if he's living on borrowed time. 自从他的癌症确诊后，他感觉自己似乎是在苟延残喘。

to continue to exist longer than expected

It is unlikely that serious decisions will be made by a CEO living on borrowed time. 重大决定是不大可能由一个苟延残喘的首席执行官做出的。