The Titanic struck an iceberg on April 14, 1912 (the ship fully sank in the early hours of April 15) and according to the NEW YORK TIMES headline which followed, there were 866 survivors. Millvina Dean, who was just two months old at the time of the sinking, was the last remaining survivor, and was the youngest person onboard (and naturally had no recollection of the sinking), and boarded the ship with her parents and brother as a third-class passenger, en route to relocate to Wichita, Kansas from England. Her mother and brother survived, but her father perished.
Because her father died as a result of the sinking, Millvina Dean had never seen James Cameron's film in its entirety [she reportedly saw several scenes featured on television]. In fact out of the six Titanic survivors alive when the film was released in 1997, only two are known to have seen the Cameron film: Eleanor Johnson Shuman (who was at the Chicago premiere where she met James Cameron; she saw the movie a few times) and Michel Navratil (who watched it at home a few years after it came out, with his family).
Surely, in three years' time on the 100th anniversary of the sinking, the movie will get a re-release.
RMS Titanic link on wikipedia.
TITANIC (1997) link at wikipedia.
Millvina Dean link at wikipedia.
A link to a youtube home video of her at an interview in 1998.
Link to Encyclopedia Titanica message boards re: Titanic survivors who saw the Cameron film.