Can iPhone viruses damage internal data such as photos?
Solution 1:
After I clicked on a link on my iPhone safari app, an ad popped up... This is clearly a virus.
No. This is a pop up ad. There is no evidence that it’s a virus.
What are the chances that is will damage the photos on my iPhone?
Zero. Did you give permissions to Safari to access your Photos library? (Is rhetorical because the answer is “no”). Safari (and every app on iOS) is sandboxed such that it cannot access other apps or data without your express consent. Since Safari doesn’t access photos, no website can do anything to them.