BillionGraves website:

#1 Log in to BillionGraves.

#2 Hover over Research on the main menu.

#3 Click Photo Requests.

You will be taken to a page that looks like this.  Requests that have been fulfilled will have a green checkmark. Those that do not have a green checkmark have not been fulfilled yet. 

Here are some related articles you may be interested in:

How do I make a photo request?

How do I find photo requests in my area?