When taking (pre)orders, you can generally bet against vendor claims for rather obvious reasons. Bitfury however is one of the few exceptions so far, delivering their asics pretty much on target (what was it, one day late?) and on spec (also in a different league than the competition, outclassing 28nm competitors with a 55nm design).

More importantly, note that BF is not pre selling anything atm that Im aware off. They got their money from VCs and only released this information long after securing the funding. They have very little incentive to lie or even exaggerate.  If it where a bluff intended to scare competition, it would be too late to have a meaningful impact.