How to handle > 200mb data file using ColdFusion

It depends on how you will be reading it. Do you know yet? You can read such files with cfhttp (yes, pointing to a csv file, and it can turn that into a query).  Or you can use CFFILE and its various actions, some which read the entire file, some which read it line by line. Same for the file* function equivalents to that.

But either way, 200m is nothing to a CF running on, say, a 1gig heap--unless of course other things runnign within CF are using up that 1g heap. Usually it would not be so, that "all the memory is already used". And many shops run with 2, 4, 8, or far more gigs of heap.

So this may well be no issue for you to handle. Only testing will tell.  And good monitoring tools (like FusionReactor, or JVM tools, or others) can help you understand how memory is used during and after that request processing.