Who is last survivor of Uchiha clan?

There is no "Last Survivor of the Uchiha Clan", but there are "Last Survivors of the Uchiha Clan" whom are Madara Uchiha and Sasuke Uchiha.

Although the "Last Survivor of the Uchiha Clan" is most likely to be Madara after Sasuke dies since Madara will live eternally, according to fan predictions.

Madara,Sasuke and Itachi.....now only Sasuke,but the other 2 are also revived by edo tensei