IMO yes. Firefox still receives security updates for Win 7.

As of right now, I don't believe there are any plans for Firefox to end support for Windows 7, although it will be ended eventually. For example, Windows XP was unsupported by Microsoft in 2014 and the final compatible version of Firefox was Firefox 52 ESR, which was dropped in June 2018. Regardless of whether or not Firefox will be compatible for Windows 7, running Windows 7 after the end-of-support date still shouldn't be considered "safe". The end-of-support means that Microsoft will no longer be releasing updates to the Windows 7 platform. This means that security issues that are discovered after that date won't be patched. This can leave you exposed to a whole bunch of security holes that can become well known and an easy way for malicious actors to attack your system. It's advisable to upgrade to Windows 10 (apparently you may still be able to [https://www.bleepingcomputer.com/news/microsoft/you-can-still-upgrade-to-windows-10-for-free-heres-how/ upgrade to Windows 10 for free]) or change to a [https://en.wikipedia.org/wiki/Linux Linux operating system], if you want to keep your computer secure after January 14.