In CVS, history was tracked on a per-file basis. A branch might consist of various files with their own various revisions, each with its own version number. CVS was based on RCS (Revision Control System), which tracked individual files in a similar way.
On the other hand, Git takes snapshots of the state of the whole project. Files are not tracked and versioned independently; a revision in the repository refers to a state of the whole project, not one file.
When Git refers to tracking a file, it means simply that it is to be included in the history of the project. Linus’s talk was not referring to tracking files in the Git context, but was contrasting the CVS and RCS model with the snapshot-based model used in Git.