Can infected root canal cause sepsis?

Yes, but rarely: A tooth that needs root canal therapy or a tooth that has a failing rct can the whole body. The infection can migrate to other parts of the body and produce infections. Happens rarely, but a good reason not to delay treatment.

Yes but rare: An untreated infection can cause such serious and life threatening problems. It is rare but this can happen. Get treatment asap.

It can happen: Any infection in the body can not only spread locally but can enter the bloodstream and cause sepsis. Fortunately this happens rarely. However, every infection should not be taken lightly & requires proper timely treatment and antibiotic coverage. Sepsis from an infected root canal would be way down on the list of infections that would lead to sepsis. In fact, i personally have never heard of this.

Yes: If the root canal was done wrong or incomplete it can get infected again and eventually cause sepsis