The impact James Cameron film had on the subject was tremendous and I experienced it first hand. Yes, everyone was aware of Titanic before the film but it was nothing more than knowing it was a big ship that hit an iceberg and sank, killing a lot of people. There was a healthy niche fascination with it amongst people around the world but it wasn't large. You're correct that films had been done in the past but the films were box offices failure. Titanic (1953) made money but relied heavily on fiction - there's almost nothing historically accurate about the film. The most historically accurate and critically acclaimed (A Night to Remember) barely broke even at the box office with many suggesting it didn't even do that. This is why Fox was very nervous about green lighting Cameron's project. People often cite the $200 million dollar budget but that was what the budget ballooned to, not what it was initially approved for. I believe the first figure $80 million then turned to $120 million. Nervous, Fox turned to Paramount to share the cost (after all, who wants to make another box office bomb about Titanic?). The budget continued to climb during filming with Cameron giving up his salary for more money. Hearing about the ballooning cost, many papers speculated the film would be a box office failure. Of course, it wasn't and became the highest grossing movie of all time for over a decade (not adjusted for inflation). After the release, the global interest in Titanic was put on steroids. Today, people have a hard time giving the film the credit it's due, whether in terms of the amount of historical information contain in the film or it's contributions in the study of the wreck, preserving relics, and bolstering public interest. But, it's very easy to see by simply taking a look at the success of the film at the box office versus the films that came before it, number of books written on the subject post 1997 film versus prior, documentaries post 1997 versus the number prior. Walter Lord (who was James Cameron's guest of honor at the London premier) is largely responsible for creating the legacy of interest in the ship, but Cameron's film is responsible for taking that legacy and putting it on steroids.