You have a few options here.
The easiest is to use Google Tag Manager and URL builder https://support.google.com/analytics/answer/1033867?hl=en
You can also use bit.ly to shorten the affiliate/CPA link, which will give you a litany of tracking options.
The hardest way would be to track referrers to the page as a view in GA, but if you are using GA, just set up the UTM and call it a day