From
the Dev's Q-and-A:
Quote
Will the MechWarrior® (that is, the player's avatar within the 'Mech) be subject to any particular effects during missions (e.g. injury resulting from hits to the BattleMech's head, falling, ammo explosions (injury as the result of an electric shock from feedback through the neurohelmet), and/or prolonged extreme overheating of the 'Mech)?
[PAUL] We are continuing to investigate what we will be able to do, but it’s a fine line between providing detail and obscuring gameplay and HUD information.
[DAVID] The MechWarrior® won’t actually take any sort of damage or be at risk of dying separately from the ‘Mech itself. However, we hope to have some visual effects like the ones that you’ve mentioned.
[MATT N] If you get shot with an AC-20 in the head the hula girl has real Hula girl Physics™!
I was the one who asked the question...
So, there we have it - official confirmation of "no pilot death separate from 'Mech destruction".
Upon 'Mech destruction, on the other hand... I believe there was some discussion on the subject, especially with regard to how a spectator mode might be implemented in such a way that the "dead" cannot become ethereal scouts for their still-"living" comrades, and such.
(I'll leave digging those discussions up to someone else...)