The 36-year old was reported missing on 17 March after his dog Max was linked to an incident in which three sheep were killed.
A member of the public reported seeing a man matching Jason's description near the Abriachan woodlands car park, on the Great Glen Way, on Sunday.
A jacket found near to where the dog was found has been identified as his.
Police have appealed to anyone who was in the area on Sunday and may have seen the man to contact them.
Mr Gates has been described as 6ft 3in, of slim build. He has short grey hair and stubble. It is not known what clothes he was wearing but he was often known to wear black jeans, a T-shirt, and a black padded jacket or a tweed jacket.
He was last seen in the Drumnadrochit area.
The area was busy with families and walkers at the time, and police are asking anyone who was there and may have seen him to get in touch.
They have also asked residents to check outbuildings, sheds and holiday homes.
A possible sighting of missing Hampshire man Jason Gates is being investigated by police.