I am currently using Firefox but i want to use TOR browser to login Bitcointalk. Is it safe to use TOR browser as i heard it is a dark web browser where hackers can hack our credentials and information ?
Tor Browser is more used for the privacy purpose. If you want to protect your identity online then tor is for you. If you think that login is not secure, then you are wrong. But you should ensure that SSL/TLS is enabled for the site where you are logging.
You can gain more information about privacy browsers here.
https://www.privacytools.io/browsers/