I would say: "He was the only survivor" or "He alone survived." ("survivor" が名詞です、"survived" is a 過去形動詞) A good longer sentence is "Of all the passenger, he was the only survivor." You can also use the phrase "lone survivor" ("lone" means 一人, but we don't use it very often).

You said, "Only he could alive. Other passengers were dead." The first one needs to be changed to be correct. You could change it to, "Only he could be alive," meaning that the only possibility is that he's the only one alive, or it could be changed to, "Only he was alive," meaning he was the only one alive. The second one only needs a 'the' added to the front to become correct. So it would be, "The other passengers were dead." You could also make this second one better by saying, "All the other passengers were dead."