Between train stations in Turin
 

What's the easiest way to go from Porta Susa to Porta Nuova

Easiest? They are connected by train.

Taxi, about 10€

Not all trains stop at both stations, or at least they did not when I was there last year.

Thanks ellenem
Were coming into porta susa from paris. Does our train continue on to Porta Nuova?

You'll have to check the schedules. If not, there may be a close train connection, or you can just get a cab.