If this year 2016, we would file our tax jointly, would I get approved for the citizenship or would I be denied?

In a naturalization application, the failure of the applicant's spouse to file tax returns should be irrelevant. If the Permanent Resident has filed tax returns as "Head of Household," however, there can be serious complications, since that generally is available only to people who are not married. It would be wise to obtain a professional opinion about the appropriateness of your filing as Head of Household - if it was lawful, then you should plan to provide evidence of its lawfulness in the naturalization application process; if it was not lawful, then you should speak to a tax professional about filing an amendment to your returns prior to commencing the naturalization application process.