Open or closed does not matter in the calculation. While open accounts is what is primarily looked at by lenders. The closed accounts while still reported to the CRAs are still used in the calculation for FICO. They can remain on the report for 10 years if closed in good standing. (ETA that many lenders do a purge anyways after a number of years so many may not make it to 10 years)
But for example if you close a CC after 20 years of use you get credit for having that history for up to 10 years after last use. Same goes for the card that was closed after 6months of use.
Bottom line though.. If you are not buying a new car or house soon then it really doesnt matter and if you can get this card to begin with your credit is already pretty good. (They typically dont approve anyone for these cards that are not already 750+)
This post was edited on 12/3 at 9:45 am