i got an answer,now i can able to apply auto complete for views export filter for that
i have created a custom module demo
in demo.module i have placed below code

<?php
/**
* Implements hook_form_alter().
*/
function demo_form_alter(&$form, &$form_state, $form_id) {
//dpm($form);
if ($form_id == 'views_exposed_form' && $form['#id'] =='views-exposed-form-game2-page') {
$form['name']['#autocomplete_path'] = 'name/autocomplete';
}
}
/**
* Implements hook_menu().
*/
function demo_menu() {
$items = array();
$items['name/autocomplete'] = array(
'title' => 'name autocomplete',
'page callback' => 'name_autocomplete',
'access callback' => 'user_access',
'access arguments' => array('access content'),
'type' => MENU_CALLBACK,
);
return $items;
}
function name_autocomplete($string = '') {
$matches = array();
if ($string) {
$result = db_select('users')->fields('users', array('name'))->condition('name', db_like($string) . '%', 'LIKE')->range(0, 10)->execute();
foreach ($result as $user) {
$matches[$user->name] = check_plain($user->name);
}
}
drupal_json_output($matches);
}