At the end of chapter 7, Nick sees Tom and Daisy conversing over a meal...she had returned to the protection of Tom's money and influence...
It seems unlikely that Tom knows that Daisy killed Myrtle because, frankly, he is not really interested in anything besides what he perceives to be a threat to his status and the status of his social class in general.
No because in the end If you read the last chapter in the book (chapter 9) during the fall (October), after tom basically confesses that he told George Wilson that it was gatsbys car that ran over myrtle and says that he had it coming because he ran over myrtle and nick says: "there was nothing I could say, except the one unutterable fact that it wasn't true." So daisy hadn't told him and this was him months later still thinking that Gatsby did it and nick couldn't say it either.
