Display no post when metavalue is 0

Here’s an updated example that appears to do what you want. See the docs for meta queries for details.

$query_args = [
    'post_type'      => 'list',
    'posts_per_page' => 3,
    'orderby'        => 'meta_value_num',
    'order'          => 'DESC',
    'meta_query'     => [
        [
            'key'      => 'post_views_count',
            'value'    => 50,
            'compare'  => '>',
            'type'     => 'NUMERIC',
        ],
    ],
];

$post_views_query = new WP_Query( $query_args );