What, exactly, goes into scores is not something that's shared by HubPages beyond what appears in the "help" section of this site.
New people start out with low author scores, but it doesn't usually take them long to see their scores go up past 75, 80, 90 if they've written some good Hubs and don't do things that will lower a score (like post "spammy" Hubs or follow hundreds of Hubbers in the belief that will get back hundreds of followers).
So it doesn't take a very "old" profile for a person to get into the 90's. I know of at least one Hubber who got to an author score of 100 within six or seven weeks of signing up.
Everybody's different, and scores can go up and down for the same person from one hour to the next (usually within a range of a few points), but it's pretty common to see someone very new have a score under 50 and days (maybe a week) later be more in the area of 70's, 80's (or so). So, I think the only way the age of profile, by itself, affects score is when the account is brand new. Beyond that, all the other stuff HubPages tells you (in the "help" section) goes into scores is what determines a person's score.