Does pancreatic cancer ever affect vision?

The word "ever" makes it impossible to answer reasonably, since I am sure that there has been a case of visual impairment in association with metastatic pancreatic cancer. Visual impairment is not usually thought of when considering the signs and symptoms of pancreatic malignancy, but an oncologist might know better than I.

Yes, any cancer can affect the eyes through metastatic spread or by paraneoplastic syndrome. https://eyewiki.aao.org/Ophthalmologic_Manifestations_of_Paraneoplastic_Syndromes. Pancreatic cancer does this far less commonly than lung and breast cancers.