If you are not able to receive email on your Gmail account then that is possible you have reached your Email box limit or it does not have left with enough space to receive any more emails. In that case you need to clean out all your email folders (Sent Drafts, Trash, Spam etc.), because these things are the main reason your email limit goes out of space and you are not receiving any email on your Gmail account.
Read also - https://onlyblog.net/what-are-common-gmail-issues-and-how-to-resolve-them/