This Gist is used to register custom payment gateway for Give.

register-payment-method-for-give.php

<?php
/**
 * Register payment method.
 *
 * @since 1.0.0
 *
 * @param array $gateways List of registered gateways.
 *
 * @return array
 */
function mg_register_payment_method( $gateways ) {

  // Duplicate this section to add support for multiple payment method from a custom payment gateway.
  $gateways['instamojo'] = array(
    'admin_label'    => __( 'Instamojo - Credit Card', 'give' ), // This label will be displayed under Give settings in admin.
    'checkout_label' => __( 'Credit Card', 'give' ), // This label will be displayed on donation form in frontend.
  );

  return $gateways;
}

add_filter( 'give_payment_gateways', 'mg_register_payment_method' );