How can I use archive-{post_type}.php theme template?

Custom post type archive page does not need “dumb” Page. In fact, there could be the culprit. You should try this:

1. Remove /* Template Name: Staff */ from archive-staff_member.php (not needed)
2. Remove “dumb” stuff Page (if created). There could be some permalink conflict.
3. Go to Admin > Settings > Permalinks and re-save it (it will regenerate rewrite rules)
4. Now just type URL … yoursite.com/staff_member/ (depends on rewrite setting in your register_post_type(...) )

You should see only “staff member” posts. If yes, than wp_query is correct and is_post_type_archive() will returns true. If it uses correct archive template too, you are done 🙂 If not (maybe 404 error?), then there is some misconfiguration.

And when you have yoursite.com/staff_member/ URL, you can add it to nav menu as “Custom link”. No “dumb” Page creation needed.