Wikipedia
Gusainji Gusaiji was the younger son of ]]. His real name was Vitthalnath. He was born in 1516 at Charnat near Varanasi. Gusaiji as Vithalnathji is mentioned in Hindu scriptures as follows: In Agni Purana, in a chapter titled "Bhavishiyotar" (Future Avatar (birth)), God himself professed that: "In future I will come as son of Shree Vallabh and I will be known as Shree Vithal."
Gusaiji led the sect Pushtimarg, the sect founded by his father after the latter's death. Based on the order of Shrinathji ( Krishna's image currently residing in Nathdwara near Udaipur), Gusainji included variation of Bhog (feasts & meals), Raag (music) and Shringaar (adorations) into the seva (day to day services) of Shrinathji. He was also the head of pustimargiya sanghatan i.e.the head of the temple trust(श्रीनाथजी).