You have a high probability in getting jail; however, it is not always certain in these types of cases. I have seen, depending on the judge and the court, individuals such as your self not obtain jail on their first violation. This is not a guarantee in any way. You should contact an attorney to help you with this. He or she would be able to put you in a good position to be successful and limit the impact. Best of luck.
Noting your location and presuming that you are reporting in that locale or a surrounding one, any violation of probation, particularly involving drug use puts you at risk for jail time. Certainly, treatment programs and private counseling can help, but you should be prepared. Be sure to note the date of your last use and to have the testing agency check the levels of THC in your system so you can show the Court that the levels are falling. Of course, it is always a good decision to retain counsel to address your specific issues.
That all depends on a lot of factors such as who the judge, what your probation officer will recommend, and how likely the judge is to follow that recommendation. While it is not the norm, from my expeience anyway, that a first violation such as this is unlikely to land you in jail, it's not unheard of either. Consult with an attorney in your area that handles such matters for a more specific answer.