When the Titanic Ship sank there were around 1,500 people killed in the Titanic disaster and searchers only found 340 bodies from the waters.
So that means that there were still 1,160 bodies left in the water somewhere that were never found and are still lost.
The Titanic ship sinking happened in the year 1912 so it's very unlikely that any remaining survivors are actually still alive today and probably have passed of natural causes.
It's been 107 years as of now the year 2019 since the Titanic Sank and those bodies that were never recovered are probably long decomposed or have likely been eaten by sharks or other marine life.