Question: What is the max file size that SAS software can successfully read.
(without considering hardware limit)

Thanks in advance.

Answer: 
Depends on HOW you read the file. If loading a hash table for instance, you are limited by memory.. If you are reading via a set or infile statement, with no or limited size output dataset, you are limited by the 'uptime' of your process - eg if / when you are forcibly logged off, or become disconnected from whatever you are reading.

Also, some datasets (eg with a large number of columns) may be impossible to read, as cannot load all the variables into the PDV due to memory limits. Again, this is an OS limitation and not SAS.
Reading from a text file, you are limited by the OS typically. Windows allows 1 million characters wide, for example, although SAS can theoretically handle a lrecl of over that.

In general, if you're asking about observations, you will be disk space limited before you are limited by anything else. I've seen a file created that were denominated in PB (petabytes, or 1 thousand terabytes) when on a compressed volume.