I would not be certain that your traffic has decreased based only on GA. Do you analyze your access logs?

Google does not always comply with noindex tags, especially when they can find and follow links from indexed pages to those noindexed pages.

Thanks for the reply, we don't analyze our access logs, it would be quite difficult to do. We are certain our traffic has dropped though over the years and have no reason to doubt the data presented in GA.

Interesting to know thought that Google may not comply fully with the noindex tags, it's not something we've tried before, but from what I've read Google should respect this directive.

If you blindly delete every page not getting traffic, you will find that the pages currently getting traffic may get less. It sounds like you need to take a serious look at your site hierarchy, including internal link structure between content pages, before you delete anything.

I'd suggest you look at ad income, or conversions if you are after those, by session and landing page. A visitor that engages and visits 3–4 pages is going to be more beneficial than a visitor that visits 1-2 and leaves.

IE: Page A earns less than Page B but visitors who land on Page A may engage more often and visit more pages, so page A, in this case, earns more PER SESSION. You need this info so that you know which pages to give more visibility to. It also helps when figuring out which types of content your visitors want.

If you're earning with display ads, there is a direct correlation between revenue and session length. Do you know which landing pages are your actual best performers per session? You won't find that info in search console, or GA without some customizing of reports.

Pageview totals and earnings per page can be deceiving, you need to know these figures per session and to know which page the visitor landed on when first arriving. Reduce visibility for pages with low engagement, not low number of visits. Your best pages might not be visible enough. Good luck.

GA may not be counting all Safari visitors, see this recent discussion: [webmasterworld.com...]

The same may apply to other 'privacy centric' browsers.

You need to analyze your access logs. There is data in that which expands and fills in blanks that ga provides. You will know more about your pages and entry points than ga can reveal.

Meanwhile, don't be in a hurry to noindex pages until you KNOW how that will affect your site!

One other thought: Noindex does not mean g HASN'T or WON'T index the page, merely means they won't DISPLAY it in the serps. G never forgets a url it has met, even the "noindex" ones!

Secondary, with over a million pages done without tanking the site, it seems evident the lost traffic is not due to HOW MANY pages, but rather a change in presentation, authority, or value. On the other hand, there are only so many top spots in the serps (after all the g stuff and ads) and the patience of any user to scroll past page one...