I'm not really sure if your question is how old is the picture or the sitter?
To answer the first question more accurately... I would have to see a pic of the back of the frame.
The answer to the second question is probably 35 - 40.
It’s me!!!!!!! I believe Bill Anderson was killed when he was 23 years old, that guy looks to be in his early 40’s. However I think I’ve seen that picture before