I94 validity and I797A validity dates

[Plmnko]

My I94 is valid until Aug 2020 (H1B visa stamp until Aug 2020 as well ) I did H1B amendment in June 2018 and new I797A had validity date until June 2021. 

Passport h1b visa stamp: Dec 1 2017 to Aug 15 2020 
Online I94 : Nov 2 2019 to Aug 15 2020
I 797 : Jun 5 2018 to Jun 4 2021

I traveled outside US and re-entered US in Nov 2019 and I am admitted only until Aug 2020 based on I94 and immigration stamp in my passport. 

Can I stay in US until June 2021 (I797) ? or only until Aug 2020(I94) ? 

My immigration attorney said, I797 validity date still will rule(June2021). But online like Murthy forum says  Latest i94 rules precedence so I have leave by Aug2020 . So I'm not sure which one to believe and what should I do ? 

If I have to leave US by i94 date , what are my options ?

Can I do h1b extension by staying inside US like go to CPB and get i94 corrected with dates from i797 ? Any other options ?

[User099]

If you have traveled and got a new I94 after your amendment was approved in June2018, then the I94 you got at the POE will be the latest I94 for you. Your I94 will expiry in Aug 2020.

You should file an amendment or travel to get a new I94. With the current situation if you plan on going to the border to get a new I94, you should call the CBP office and confirm if they can do it. You should also plan on doing it before your current visa stamp expires.