Cannabis use among those with Hep C is higher than in the general population. This is likely because cannabis can help manage the harsh side effects of interferon and ribavirin therapy, which was previously commonplace for Hep C treatment. Newer antiviral regimens are available which can treat Hep C with more tolerable side effects.
There is no data to suggest that cannabis products help to treat Hep C itself. However, there is also no clear evidence that cannabis products harm those with Hep C disproportionately. A relatively recent study in 2014 (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4144456/) found that cannabis use among those with Hep C did not alter outcomes substantially although a previous study did show that cannabis use was associated with higher fat accumulation in the liver among cannabis users with Hep C (https://www.ncbi.nlm.nih.gov/pubmed/18242211).
If you are taking CBD oil or using other cannabis products, it is not likely affecting your Hep C treatment to a large extent. It is important to reiterate that there is no evidence that CBD oil can treat Hep C itself. Antiviral medication is the standard of care for treating Hep C. You should discuss your cannabis use and overall Hep C treatment plan with your hepatologist. Sharing this information with all of your physicians is critical since cannabis use can affect your eligibility for transplant in the future.