If no cache headers are provided (no Cache-Control or Expires) and the url is cacheable (.jpg, .css, .js etc.) then Cloudflare caches both 301 and 302s. We cache 301 for a couple of hours and 302s for a shorter period of time (~20 minutes).
However, if the headers are set, they override these defaults. In particular, Cache-Control: private, no-cache or public, max-age=0 (or some combination) will tell us not to cache.
For urls that do not get cached, if you want to cache the page, you can create a Page Rule and select 'cache everything'. This will make the resource cacheable, as long as the headers allow it.