Smegol's existence really stretches the definition of "alive". Yes, he we still a physical being of flesh and blood, but his life such as it was, was wretched and fixated solely on the One Ring. That's not living in any meaningful sense.
Remember that the nine didn't appear as actual ringwraiths until about 700 after the forging of the rings of power. It took that long for those men to become totally subsumed by the rings, and enslaved. On top of that I'm pretty sure that they didn't loose their physical form until Sauron lost his when the ring was cut from his finger.
Sméagol by contrast "only" had the ring for 500 years, and Halflings have proven to be much more resistant to the ring than men.
So yeah, if we could see one of the nine a few centuries prior to becoming actual wraiths, they'd probably look just as "alive" as we see Golum in the books.
