Edit 3

Now, combine Edits 1 and 2:

'date_query' = > array(
    array(
        'before' = > strtotime( get_the_date() ),
        'inclusive' = > true, 
    )
)

Edit 2

You don’t have your inclusive parameter inside the correct array.

Change this:

'date_query' = > array(
    array(
        'before' = > get_the_date()
    ),
    'inclusive' = > true, 
)

…to this:

'date_query' = > array(
    array(
        'before' = > get_the_date(),
        'inclusive' = > true, 
    )
)

Edit

The get_the_date() function must be used inside the loop, because it relies on the $post global.

The get_the_date() function also returns a date-formatted string, but the date_query before parameter accepts a strtotime() compatible string.

Instead of this:

'before' => get_the_date()

…try this:

'before' => strtotime( get_the_date() )

Original Answer

The inclusive parameter is part of the WP_Query() date_query parameter, and must be used inside of the array passed to date_parameter. Refer to the example usage in the Codex:

$args = array(
    'date_query' => array(
        array(
            'after'     => 'January 1st, 2013',
            'before'    => array(
                'year'  => 2013,
                'month' => 2,
                'day'   => 28,
            ),
            'inclusive' => true,
        ),
    ),
    'posts_per_page' => -1,
);
$query = new WP_Query( $args );