What happens when a RC4 stream gets corrupted? I want to encrypt a large file using RC4. But what happens if the encrypted file gets corrupted (bytes modified or lost)? Can I still decrypt the rest of the file correctly?

If not, what is the best solution? Split the file in X chunks, and encrypt those seperately?
If a large file enciphered using RC4 is partially corrupted, the uncorrupted portions remains fully decipherable, including what's after a corrupted portion if the corruption modifies this data's value, but not its length (a length corruption could occur e.g. for serial communication, but is unlikely on a hard disk). This is a property of all stream ciphers.

An exception is when there's an IV somewhat combined with the key to form the full key input of RC4, and this IV is corrupted; then the whole file is undecipherable, essentially as if the key was lost.

Another practical exception is if the deciphering program somewhat stops when encountering a corrupted disk block, or gets the keystream out of sync with the ciphertext in this situation (which is not unseen!); to recover from this without fixing the program, the corrupted file can first be copied to a good media, with the corrupted blocks replaced by arbitrary data (rather then removed).

Finally, the deciphering program could include a provision to check file integrity, and refuse to output the plaintext if it is corrupted; in that case, this deciphering program needs a change to skip this check.