gravityforms-date-selection.php

<?php
/**
* Filters radio choices to include the next 14 days
*
* Place in the theme's functions.php file
* @link https://docs.gravityforms.com/dynamically-populating-drop-down-fields/
*/
add_filter( 'gform_pre_render_1', 'populate_dates' );
add_filter( 'gform_pre_validation_1', 'populate_dates' );
add_filter( 'gform_pre_submission_filter_1', 'populate_dates' );
add_filter( 'gform_admin_pre_render_1', 'populate_dates' );
function populate_dates( $form )
{
    foreach ( $form['fields'] as $field ) {
        if ( $field->type != 'radio' || strpos( $field->cssClass, 'date-radios' ) === false ) continue;
 		$dates = [];
 		for ( $i = 1; $i < 15; $i++ ){ // (change to 0 and <14 to include today)
 			$dates[$i] = [
 				'text' => date('M d, Y', strtotime('+' . $i . ' day')), // The label
 				'value' => date('M d, Y', strtotime('+' . $i . ' day')) // The submitted value
 			];
 		}
 		$field->choices = $dates; 
    } 
    return $form;
}

The above filters the radio field with a css class of "date-radios" under a form with an ID of 1.

The list of choices is returned to include the next 14 days.

Date formatting can be updated as needed for the label and value.