Is AES unbreakable even till date?
If you mean via cryptoalgorithms weaknesess and brute force attacks. A cipher is considered to be strong when there exists no current practical method of breaking it. This does not mean in the future that a method will not be devised. Well studied ciphers such as AES, Twofish and Serpent should be good for maybe 10-20 years. So bear that in mind. They may be strong by today’s standards but in the future there could be practical attacks.
Theoretically, 128-bit keys can be broken on a future quantum computer. So you should be using 128-bit keys as a minimum. In December 2015 NASA publicly displayed the world’s first fully operational quantum computer now owned by Google. Its still pretty basic but there coming.