Jihadists can win if they apply themselves while being in war and make sure to keep their plan of action the whole time they are in war because keeping a plan is very important during a war. I think that they will be victorious if they also stay positive during the war because positivity is key when you are in any situation.
It is impossible to tell who is going to come out on top in the Syrian civil war. A lot of it depends on whether or not international aid will step in to help against the Assaad regime, or if they will let the country fight their battles to see who wins. Right now, it is impossible to tell.