Do you think employers take into consideration the moral state of the person they're interviewing, for instance how nervous he is during the interview?

of course it take in consederation it's very importing

For their decision I would say DEFINITELY.
They look at every detail.
Even the expression, the movements, the tone, the eye contact, the way you're sitting.
But honestly I never was nervous at an interview whatsoever.
The word "stress" doesn't exist in my vocabulary.