The document is a PDF on my Google Drive. I have to print it at the airport because some paperwork officials want a hard copy, and I may not get the document prior to my arrival at the airport.
The Airport Travel Agency (https://www.airporttravelagency.org/) offers the following services on their website:
- computer use
- fax and copies
While they don't mention specifically the possibility to print something, both mentioned points combined should give you the possibilities to do it. They are also not labelled as "temporarily closed" on the SFO website, so i assume they are open during their regular opening hours.
If you don't find an official place (lounge or the agency in dunni's answer) your last straw may be to walk up to places like stores and other counters which appear to have a printer and ask them to print a document for you, perhaps with the promise of a Latte Venti or something. I'd try to be as charming as possible and preferably approach a member of the opposite gender (or, more generally, somebody attracted to mine).
When I was in the same situation in Berlin, the airline counters appeared to have a strict policy not to do that. Therefore, better ask in stores selling mobile contracts etc. which surely have a printer and may have more freedom from corporate policies and more incentive to be customer friendly.
That said, in the comparatively little Berlin Tegel airport I did not succeed back then, but luckily the check-in counter had my ESTA information online and didn't need a hard copy in the end. (I had success with that strategy at another occasion which was not in an airport though, so perhaps the clerk didn't have the same default self-defense attitude common in crowded places.)
Therefore, this is only a last straw and not a reliable recommendation.