Is it possible for a tubal pregnancy to reach 6 months or the mother would have died already from a rupture ?

Tubal PG rupture: Tubal pregnancy rupture usually occur at 10 to 14 weeks gestation as the Fallopian tube musculature can no longer contain the expanding pregnancy. Thus 6 months of tubal pregnancy is extremely rare, but not abdominal pregnancies which grow in the abdomen outside of the uterus. A ruptured tubal pregnancy results in massive life threatening hemorrhage.

Very rare: A tubal pregnancy almost never makes it to 6 months. There have been a few cases of pregnancies outside of the uterus surviving to term but this is very very rare. When it happens it is written up in a medical journal: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3158531/ Best wishes!