Swager,
Nope. If you read the development history of the H8K you'll see that it is an independantly developed design. It is considered to be the single biggest jump in flying boats ever. You don't get that by making a copy of somebody else's design.
Also look at the Short Sunderland. Was that also a copy of the Pacific Clipper? The fact of the matter is that Flying Boats being, well, boats places heavy limits on the types of fuselages that are appropriate. Big flying boats all tend to look something like the Pacific Clipper / H8K / Sunderland.