From reading your question, I assume the following things.
- Your post(s) are related to an author (user)
- Your post(s) are related to a term in the Custom Taxonomy “members”, which would have the same slug as a users nicename/username/something.
First, may I recommend losing the ‘Members’ taxonomy, as Users already have author pages which can be customized author.php. You can create a secondary WP_Query here and list any posts you want attached to that author.
If you want to relate the two together, you’ll have to get the post author, then do a compare of the term label/slug to some item on the user. Something like:
$term = get_term_by( 'name', $post_author->first_name . ' ' . $post_author->last_name, 'Members' );
$term_link = get_term_link( $term->term_id ); // mysite.com/members/john-doe
One other thing to note is the template for a single term in Members would be taxonomy-members.php for a general term template, or taxonomy-term-john-doe.php for a specific term.