Well it can't be 2012 AD, anno domino, which we have interpreted as after death. He was somewhere between 33 and 36, according to what source I don't know, when the Romans crucified him...so that would make him 2045-48. Which means he'd probably be living in Delray Beach, chewing a cigar and driving really badly.
The best guess as to the year of birth for Jesus is about 5 BCE, give or take a year. This is due to Herod the Great being alive at his birth, and he died in 4 BC. There is no year 0 AD; we pass from 1 BC to 1 AD without a hiccup. Doing the math, if he were alive today and measuring from his earthly birth (some say he was spiritually pre-existant), we get 2016-2018 years old. Of course, several NT verses say he created the earth, so that makes him billions of years old. It's hard to give one answer to the question!