Is Owen's death destiny, or did he pave his own path? This is a question that we're still puzzling over. Owen seems to believe pretty strongly from the time he's a young boy that God has plans for him and that it's not his business to mess with them. On the other hand, other characters like John and Hester seem to be more of the mind that things happen because we will them to happen. In A Prayer for Owen Meany, Owen's belief in fate and God's plans leads him to the army and to his ultimate death. Whether or not you think Owen's death is a product of fate or of choice is up to you. Either way, it's an interesting matter of debate.
The events leading up to Owen Meany's death show us that he was destined to die on the day that he died.
The events leading up to Owen Meany's death show us that there were many choices he could have made that could have helped him avoid his death.