It's hard to tell as there are no published information about which particular hand Tupac use. However, we think that he is right-handed as there are photos of him using a pen, holding a mic and even smoking using his right hand.
Tupac Shakur via kwout
On the other hand, there are photos of him showing that he is wearing his watch on his right wrist. Left-handed people typically wear their watches on their right wrist, just as right-handed people wear their watches on the left wrist. There are also some photos of him smoking using his left hand.
It is commonly estimated that about 10 percent of the human population is left-handed or ambidextrous. Boys are about 1.5 times more likely than girls to be left-handed. Archeological evidence indicates that the proportion of left-handed to right-handed people was about the same 30,000 years ago as it is in the early 2000s. Learn more about handedness at Encyclopedia.com.