When I worked at Moss Bros as a child, a few holocaust survivors worked in the tailors dept, they kept themselves to themselves but we're very kind to me, and got me out some messes when I got my fitting measurements wrong.
A teacher at school was a survivor, never a personal tutor of mine, but at meal times I remember she would get angry if kids wasted food. I now understand why.
i have been to a few talks held at libraries given by survivors, always treasured the fact they wanted to teach about intolerance.
I would never deny the holocaust, but like with any subject, critical thinking needs be applied to the books we read. Calel Perechenik, Autobiography " Am I a murdereer" and "The death Brigarde" by Leon Wells, are two books that present irrefutable evidence gas chambers were real. I have never found concrete evidence of the actual figure that were killed in the gas chambers, but I have zero tolerance for those that deny the holocaust happened.