Capacity of Advanced Encryption Standard in terms of File Encryption what is the capacity of AES in terms of File Encryption?
is it really good to encrypt a large files in AES? ex. I am encrypting a 8GB of File... is it still good to used AES? 
is it still good to used AES-OFB in encryption of large files?

What also will be the issue if I used AES-ECB in file encryption? is the only issue will be the odds of having a same 128-bit block of data?
If you mean how much data can safely be encrypted by AES with a single key (and IV), AES is designed to encrypt up to $2^{64}$ blocks of data before becoming susceptible to certain statistical attacks (in particular distinguishing the encrypted file from truly random data), because of its 128-bit block size. 8GB (= $2^{36}$ bits = $2^{29}$ blocks) is quite below this limit, you are fine.

That said, AES-OFB alone is not enough, as it is a streaming mode the plaintext can be altered rather trivially assuming it is partially known beforehand. You will want something like a HMAC on top to ensure the file does not get corrupted by an attacker at some point (note that this does not mean a block mode like CBC does not need one - it does, but plaintext cannot be altered in such predictable ways)