Uddhava Das is an avesha incarnation of the Moon-god.
(Gaura-ganoddesha-dipika 192)
In the Chaitanya Charitamrita (1.12.83), it is said that Uddhava Das is a branch of Gadadhara Pandit Goswami. As such, he is mentioned by Yadunatha Das in the Shakha-nirnayamrita (35):