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.