As far as I know, there has been no event yet in the manga where Eri was shown to have reverted a dead person back to life.
What we know is that:
- Her quirk can only affect a person's physical state, as mentioned by Aizawa in Chapter 161
- Her quirk can erase a person's existence completely, as mentioned in Chapter 156, when her father accidentally touched her
Personally, this is still vague. For example, does a person have a soul? Because if he/she does, will the soul alongside the body be also affected? What is only known is that her quirk can only affect the physical state of those she is in contact with or within her vicinity. There is a possibility that, if a person does have a soul, it can also be affected, unless the manga dismisses it entirely. Is there a guarantee that if a person has a soul, would his/her soul still be near its physical body upon death? Near enough to be affected by her quirk?
However, assuming that a person does not have a soul and death is just another physical state of the body in the My Hero Academia world, then theoretically, she could.
There are still much to know about her quirk that we can only speculate what could be or could not be possible. As far as I know, that manga has yet to clarify this.