Hello Artorius Maximus: I'm sorry I do not know the answer to your question. One thing I do know is that guilt & shame, as well as worry, can themselves cause a man to lose his ability to maintain an erection. So my thinking would be that even if the viewing of porn itself doesn't cause problems, the guilt, shame & worry that often accompany it may well do so. Plus the simple process of aging can contribute to these sorts of problems as well. Under any circumstances, I'm not aware of any specific treatments that are available except for ED med's, of course.
I see this is your first post here on PC. So... welcome to PsychCentral… from the Skeezyks!

I hope you find the time you spend here to be of benefit.
PsychCentral is a great place to get information as well as support for mental health issues. There are many knowledgeable & caring members here. The more you post, & reply to other members’ posts, the more a part of the community you will become.

Plus there are social groups you can join & chat rooms where you’ll be able to connect with other PC members in real time (once your first 5 posts have been reviewed & approved.) Lots of great stuff! So please keep posting!