Any file encrypted with a password that can be taken from online and stored offline, given enough time, can be decrypted, it depends of the attackers speed in which he can iterate passwords and how strong enough is your password.

Let's say you break that archive into multiple ones, still mostly the first file has headers which can lead to revealing some information.

You are also depending on 7Zip using AES encryption bug free and/or being certain that there are no security/encryption back-doors.