when stepping with the jab is it best to step across and to the left a little at the same time to widen stance when coming in or is it better to step straight forward.Or would it depend on situation for instance if i was trying to work my way inside or if i was trying to keep opponent at range?

Hate to say it,depends
To many possible factors,is the guy a good counterpuncher,southpaw or orthodox,where you are in the ring at the time,etc....

Well when we first teach peolpe there jab we teach to take a slight step to the left when they jab,but after u know how to throw it you don't neccessarily have to,but it is kinda natural to and it sets up your right hand better with more power if u move to your left rather than your right or straight in,but different situations will call for u 2 step at different angles