What would the likeliness be of Neanderthals or Ape men existing or still existing in the dense forests of Siberia?

I had been watching a video on a sighting dubbed 'The Russian Bigfoot' in which during the final days of the Russian Civil War, the soviets had been sending out patrol's of soldiers to hunt down the last of the white army when it was reported that they were attacked by a creature that was said to be 'half man and half ape'. The creature was described to be 5 and a half feet tall covered in redish looking hair and had considerably larger toes and feet than a normal humans. I did some research and some theories on the sightings are that it could be a surviving species of Neanderthals. I did some research and there have been reported sightings across Central Asia and Siberia of these creatures. So I was curious to know, what are the odds of a small group of Neanderthals surviving in the thick forests of the Siberian wilderness?