Transferring is one thing. Will a 1GB file display in an app on the iPad? The thing doesn't have that much ram.
It's not a matter of RAM. I have several movies on my iPad, one of which is 2.5GB in size.
RAM may or may not make a difference. Some documents, like movies and music, do not need to be completely loaded in RAM, because they play sequentially. You can load what you need as you go.
Other's like spreadsheets need to be completely in RAM (or simulated RAM), or all the calculations may not work.
Power Points could fall either way, or probably more in between. They are mostly sequential when being displayed, but tend to need to be all there when being edited. A smart program could switch things in and out of RAM as needed. I don't know if Keynote is that smart.
At any rate, I remember another poster who had a 1.5 GB Power Point that he definitely could not get to run in Keynote. So, I don't know if 1GB will work or not. The only way to find out, since no one seems to know actual specs, it to try it and see.