live on

If you live on an amount of money, that is the money that you use to buy the things that you need:
We lived on very little when we first got married.
I can live on my inheritance.
The job provides enough to live on.
His earnings aren't enough to live on.
They live on the money they earn from growing tobacco.
It's hard to imagine what these people live on.

to only eat a particular type of food:
I more or less live on pasta.
(Cambridge Advanced Learner's Dictionary & Thesaurus からの live on sth の定義 © Cambridge University Press)

ビジネス英語
if you live on an amount of money, that is the money that you use to buy the things that you need:
Nearly 5 million of Morocco's 33 million people live on less than $2 a day, according to the World Bank.
live on a budget/a low income/a fixed income etc. Many retired people living on fixed incomes need to estimate what the purchasing power of money will be over long periods in the future.
(Cambridge ビジネス英語辞典 からの live on sth の定義 © Cambridge University Press)

- Cambridge Dictionary