Officials said the son of the owner of the popular eater Krishna Dhaba was shot dead in a hospital in Srinagar on 17 February.
Akash Mehra was undergoing treatment at SMHS Hospital for the last 10 days.
Officials said that Akash Mehra died in the early hours of Sunday.
Police said that he was shot dead closely by the militants and was seriously injured.
The Muslim Jambaz Force, a terrorist organization active in the early 1990s, claimed responsibility for the attack.
Krishna Dhaba, famous for serving vegetarian food, is located in Durjanag, a high-security area of the city. Several high-profile installation meals such as the Office of the United Nations Military Observer Group for India and Pakistan and the residence of the Chief Justice of Jammu and Kashmir are located within 200 meters of the food joint.
Police arrested three people for their allegiance to a shadow militant organization of the banned Lashkar-e-Taiba for involvement in the attack.