Need advice on Release

After I cleared 1st interview, they hold my position for 2nd round & told me currently they are looking for 1 month np. Me jhooth bola tha ki 1 month notice period possible he in current situation as currently tcs is in restructing phase . Now they release offer letter & want me to join in 1 month. Before released OL, I have asked my Manager, is it possible to release in 1 month , he told 2 month minimum. If I resigned, what if they revoke OL ?
If revoked ,what if tcs not want to withdraw resignation?