If you know the hiring manager and he/she likes you, that will be a big plus.
In USA company, usually, the hiring manager make the decision, and let his
manager get informed, or get one more layer approval.
good luck for your job hunting.
Please visit my website and join my Wednesday night's free tele-conference
call to ask or share job hunting questions and experience. Everybody is
welcome.
You can also listen the record of previous tele-conference from my web-site.
Have a nice day!