FWIW, Google AI (if it's not hallucinating) seems to remember it; and returns the following detailed description of the ad for a Fujica ST701, yet it does not provide the image itself:
1970s fujifilm (fujicolor) advertisement. setting: the photo features a young couple at a café in san marco square, venice, identifiable by the pigeons and historic architecture in the background. composition: they are sitting at a small round table, sharing a single tall glass of coffee or a cold drink with two straws. product placement: a fuji camera (often identified as a fujica st701 or similar model) sits prominently on the table next to the glass.
EDIT: browsed many, many 1970s magazine ads for Fujica cameras. Advertising budget must have been big. This one not found. Gomen-nasai!