The X1D will ship within 7-14 days at BHphoto. This is the first time I see such a short shipment time in US. The Fuji GFX is now in Stock since a couple of weeks at Amazon US.
UPDATE: Dpreview just published their X1D firs impressions review. And the X1D seems to have an edge over the GFX when it comes to Dynamic range:
This greater definition in deep shadows allows the X1D to surpass the Fujifilm GFX 50S in extremely pushed, base ISO shots. Bill Claff’s independent analyses confirm the 0.08 EV advantage in base ISO (photographic) dynamic range over the GFX, and the X1D’s lower read noise.