How did the Jews at concentration camps view their existence when death was a probability?

I am not sure anyone can answer this with great certainty
unless they were there to experience such a reality.  The other way this question can be
answered is through survivor testimony or reading the thoughts who were there.  This
would be where sites like YouTube are so important in that we can seek out survivor
testimony and learn from it.  We, as modern individuals, can learn how consciousness
functions under the looming shadow of death at any time.  How does random selection and
a sick sense of probability figure into living one's life?  How does one love, enjoy
life, or see "another butterfly?"  The other option would be to read works from those
who endured the experience.  Of course, one cannot go far here without reading Elie
Wiesel's narrative, "Night," which talks about how a young boy, Eliezer, endures life at
the camps with death as something that is real.  It shows how the stripping away of his
humanity was part of this equation, renouncing community, spirituality, family, and hope
in order to live.  Another step in this process would be to examine writings from and
inspired by The Holocaust.  There is a great book of poetry entitled (appropriately
enough), "Holocaust Poetry" that features many poems which deal with how one lives life
in the face of constant death.  It is a wonderful read that brings out the pain and
sorrow, the agony as well as the hope of redemption that are all intrinsic to any
worthwhile study of the Holocaust.