Total travel time from Naples airport to Sorrento train station?

If you want to go to train station why take the ferry?

NAP to Sorrento via train would take maybe 1.5 hours, ferry about the same if schedules line up

Your question is confusing

Well, it depends.

There is no train from the airport to the train station, or the ferry port. There are public buses, shuttles, taxis, and all types of people outside the terminal doors offering a ride to one or the other.

I suppose once you have secured a ride, or the bus takes off, it is 15 minutes to the train station, 30 if traffic is bad, a bit longer, maybe 30 minutes to the ferry port, but worse in heavy traffic. Though it is a bit unclear whether you are comparing the two routes, or taking the ferry, no need to go to the train station if going to the ferry.

The train, the Circumvesuviana, takes just over an hour to get to Sorrento, about an hour and 10 minutes. Trains leave every half hour, so figure once to the station, finding the Circumvesuviana station, getting tickets then maybe get right on a train, or wait a half hour. So who knows1 1/2 hours to 2 hours?

There is the Campania Express, but fewer departures, and since it runs on the same track, despite the express name, it is no faster. It costs a bit more, but that gets you some space and air conditioning, if it is working.

There is a direct bus from the Naples airport to the Sorrento train station that's perhaps the easiest way to get there. You can look up the timetable to get an estimate of how long it takes, although part of your "total travel time" is going to be the lag between when your flight arrives and when the next bus is scheduled.

There is a direct bus from the Naples airport to the Sorrento train
station that's perhaps the easiest way to get there.

But that doesn't have anything to do with the Op's question about a ferry from Naples (NOT the airport) to Sorrento. That's why we're all confused!

It's not clear from your question but I think you are flying into Naples then later boarding a ferry from Sorrento to one of the islands like Capri maybe??? (check to see if you can get a ferry directly from the Port of Naples to your island)
... or Maybe you are thinking you need to take a ferry from Naples to Sorrento?? (you don't)

But IMO the best way to get from NAP to Sorrento(and vice versa) is by taking Curreri Viaggi direct bus that has multiple daily departures. It costs something like €13 and takes approximate 1:20 depending on traffic. It drops you at the Sorrento train station. If you need to go to the Sorrento ferry dock (Marina Piccola) it's a 10 minute walk to the public elevator down to the seafront followed by a <5 minute walk to the actual ferry dock. You could get a taxi to eliminate some of that but the walk is all down hill and very easy.

I would highly recommend contacting Aldo Limos. Have a stable of. Nice Mercedes Benz sedans and vans. They picked us up at the Naples train station and transferred us to/from our hotel in Sorrento. They could do the same from the Naples Airport. Can’t say enough about Aldo Limos. We used them 3 times The drive was about 1.5 hours. Good luck.