I have a question for re-entering to U.S with H1b visa 1 week left on expiry

In theory you should still be allowed in, because it's the validity date of your USCIS issued I-797 Notice of Approval that controls your admission back into the country. In practice, however, with just a week left to expiry, you are sure to raise the eye brows of CBP inspectors at the airport. You will be questioned about your intentions one week after admission, etc. The CBP at the airport have a lot of discretion whether to admit you, for how long or not admit you at all, despite a still valid visa, status or otherwise. That is why I wouldn't "play with fire" and stretch my absence from the U.S. (where you are supposed to be "working" under H-1B status) and return with just one week left to your expiration date (and I understand with no proof that an application to extend your status has been filed). The best that could happen is that you would be let back in for just one week, or simply denied entry, if after being sent to "secondary inspection" it will result from the investigation that you ceased working for the H-1B petitioner some time ago already, or never in fact worked for him, and that now you are simply returning in order to try your luck in finding another H-1B employer to "transfer" your visa to.. Of course, if you return with at least 6-8 weeks left on your visa, after a "brief" absence, you will be facing less scrutiny at the airport and can always explain that a petition to extend your status is in its final phases and will be filed by the employer soon. Last, but not least, I will also recommend that you come with a letter from your employer confirming the fact that you are still employed, your job duties, pay, etc. and have your last year's W2 and 3 most recent pay stubs with you to show to the officers in case asked.

I agree with my colleague.