If you're talking about tapestry no he wasn't he died on the table after they beamed him up.
No, I'm thinking about Who Watches The Watchers. The same thing happens to Harry Kim and an alien in Emanations. They were all dead, beamed, and revived. If you were trying to make the argument that people must retain consciousness during beaming, nope, sorry, not so much.
You are confusing the status of being conscious (i.e., being awake) with the status of possessing consciousness (i.e., having a mind).
I would draw a distinction between clinical death and information-theoretic death
. A person might be clinically dead, yet the information that comprises their personality still present in the brain and capable of re-activation if the clinical death (cardiac arrest, etc.) is reversed.
Tuvok and Neelix, I would argue, underwent information-theoretic death. The information that comprised their minds was disrupted; the systems which are their minds were terminated. A new system comprised of corrupted copies of that information was created -- Tuvix, and then Tuvok 2.0 and Neelix 2.0. But none of these three beings were the same information systems as the original Tuvok and Neelix.