"how many restaurants is one life worth?"
It would take quite a few restaurants. However, you are ignoring the fact that letting all of the restaurants close will also kill people. I don't know how large this effect is, but we also don't know how many people will get COVID due to restaurants being open. It's complicated.
As a society we are okay with people driving cars, yet we know automobile accidents kill people.
I would ask you: How many car trips are worth one life?