Answer:
The exact number is unknown, and there are different definitions of Holocaust survivor.
"When the war ended on 8th May 1945, it is estimated that there were around 200,000 Jewish survivors of the forced labour camps, concentration camps, death camps and death marches. Thousands of other survivors, who had been with the partisan groups, or in hiding, were also freed from Nazi control. The majority of those who survived were aged between 16 and 40 years old. The death toll continued to rise after liberation, with tens of thousands dying of starvation, disease, and the after-effects of malnutrition."
The Holocaust wiped out around two-thirds of the European Jewish population, or one third of the world Jewish population.
Source: Zoe Vania Waxman, Writing the Holocaust, Oxford University Press, 2006