The failure rate for tubal ligation is said to be 1.85% especially after passage of some years. Thus you can get pregnant even with your tubes tied. However most of such pregnancies are ectopic pregnancies which are dangerous as the baby develops out of the uterus.
No, the baby cannot live in the tube.
It is impossible for a woman to carry an ectopic pregnancy to term as the feutous cannot receive the protection and nourishment it would if in the womb. An ectopic pregnancy is dangerous to a woman and needs to be aborted. Your friend, if carrying an ectopic feutous will soon suffer severe abdominal cramps if the pregnancy continues. My question is How does she know it is ectopic. She would have to have seen a doctor to know that and he would have hospitalizied her.