My Epson Pro Stylus 7890 no longer centers prints from the Photoshop CS6 print dialog box, although it does in Preview. (Mac) The Epson Technician referred me to "talk to someone at Adobe" I am typing here because I can't find where I can get live help.
Adobe doesn't really have a choice in that - the printer driver controls the printable area and page dimensions that Photoshop can center the image within.
Epson's driver software controls the page information, including all page and printable area data.
If you're on MacOS 10.9 - Epson's drivers have a lot of problems on 10.9.