In Pages Is there a way to identify the date a document was originally written?

Yes, with AppleScript.

Copy/paste the script into the AppleScript/Script Editor, click the hammer icon to compile it, and then save as an Application (hidden extension) to your Desktop. When you have a Pages document open, just double-click this cdate application and you will get a dialog showing the path to the document and its creation date.

tell application "Pages"

activate

tell front document to set fpath to its file as alias

set ctime to creation date of (info for fpath)

set thisfile to POSIX path of fpath

display dialog thisfile & return & ctime as text with title "Document Creation Date"

end tell

Then no, there is no means to get the creation date of a Pages document from within Pages for IOS.

However, if you look at the gallery of Pages documents on Pages for iCloud, the creation date is shown below the document icon. The Finder Get Info will also report the document creation date when you select a Pages document on iCloud, or iCloud Drive.