Eddie Willers periodically ate dinner in the Taggart cafeteria with the Mystery Worker (who is, of course, later identified as John Galt). They discuss a lot of different things, including the state of the world and Taggart Transcontinental.
With that said, given the fact that much of the concrete information Eddie supplies to the Mystery Worker is promptly used by the Strikers to the detriment of Taggart Transcontinental, why didn't Eddie ever put two and two together (especially given how obviously pointed a few of the Mystery Worker's questions were)?
For example, Eddie Willers mentioned that Dick McNamara was going to be the contractor on the John Galt Line to the Mystery Worker, and he disappeared shortly after that.
He mentions their great need of diesel engines and who they'll be ordering them from. The Mystery Worker pointedly asked about how critical the diesels were, and the would-be manufacturer promptly disappears.
Same thing for Quentin Daniels (although admittedly the disappearance of Daniels was kind of overshadowed by the simultaneous disappearance of Dagny herself, along with the fact that Quentin Daniels was working for Dagny directly rather than through Taggart Transcontinental).
There were a number of other strange occurrences with information that Eddie shared with the Mystery Worker. So why didn't Eddie ever figure out who he was?