I just think it's a gross oversimplification to think that Tuvok and Neelix were in any way "dead." Tuvix was not a completely separate person; he was both of them at once. Think of it like a mind meld, when two personalities are so blended they function as one being. The melders aren't "dead" once that happens, just blended. It's just that in this case they were blended physically as well.
I mean, let's turn it around. Will Riker was one individual who was then split into two by a transporter accident. The two separate Rikers developed distinct personalities and lives. But does that mean that neither Riker was "alive" before the transporter split? No -- in a sense, they were both there in potential within a single individual.
Frankly I would consider Janeway a horrible commander if she treated the question as simplistically as you folks are. That would be a criminally irresponsible way of reacting to a situation as unprecedented and unique as this one, one that raised so many difficult questions and issues. Just trying to force a totally new situation into some pat, conventional set of definitions is anathema to the open mind a Starfleet captain needs in order to cope with the new and unknown. The only responsible thing for her to do would be to consider all the possibilities and not just glibly assume she was qualified to define life and death in this unique situation.