Well, it is hard to say, since he is a robot (not lying, see Ninjago Rise of the Snakes Episode 7 Tick Tock). But, we can assume he is about 50-60 years old since his creator died of old age.
I agree that he's like 50- 60 years old, but his dad isn't dead...........ANYMORE! I did research and i found out that in episode 22 of ninjago, it is revealed that not too long after Zane's memory switch was turned off, Samukai found Zane's dad and used a potion to bring him back to life. Just look at Lego Wiki!