The woman was First Class Passenger Mrs. Elizabeth Lindsey Lines. She was traveling with her daughter, Ms. Mary Conover Lines. They were both in the First Class Lounge when Mrs. Lines overheard the conversation and received a confirmation that it was Captain Smith and Bruce Ismay, who were discussing lighting the last of Titanic's boilers, so as to best the crossing time of the Olympic's maiden voyage.
No one knows for sure, so your guess is as good as mine. As Roy said, it's just a draft of what really took place. It may very well have been used for dramatic license, which is quite common in Hollywood.
>>"This maiden voyage must make headlines!" Did he really say that?
According to what I've been able to read of Mrs. Lines' testimony so far, no, he didn't. The very one-sided conversation was mostly regarding the length of the days' runs, the condition of the machinery and boilers, etc. One statement of Ismay's that really stuck with her was, "We will beat the Olympic* and get into New York on Tuesday." [*re: her maiden voyage time.]
She was also asked:
Q: "You have stated several times, Mrs. Lines, that Mr. Ismay made assertions or statements as to what "we" would do, using the pronoun "we". Did he use any other pronoun that you know of in this conversation?"
Lines: "No, Mr. Ismay said "we" and he asked no questions. He made assertions, he made statements. I did not hear him defer to Captain Smith at all."
Q: "Won't you describe as well as you can, the tone and gesture of Mr. Ismay in this conversation?"
Lines: "It was very positive, one might almost say dictatorial. He asked no questions."
A much larger chunk of Mrs. Lines' 1913 testimony is included in George Behe's book, "Titanic: Safety, Speed and Sacrifice."
Re: the movie quote, I'd say there's no doubt at all that headlines were on Ismay's mind. And BTW, within the context of the film, I'll stick by my use of the word "sinister."