I'm pretty positive that the power requirements on the Fabricator are very deliberately high, to avoid exactly that. If you're flush with power and you need lava for other things, that's one thing, but if you want to use it for power, I strongly doubt it's possible. I'm not 100% though!
I haven't run the numbers on lava power in 1.10, but the only positive feedback loop from 1.7 involved the MFR Lava Fabricator or to a lesser extent the TE Magma Crucible. The MFR Lava Fabricator provided a stable source at a constant rate and power, and it could easily create enough to power itself if you put it in a MFR Steam Boiler and fed that steam to a variety of power generation methods. The TE Magma Crucible required more power overhead to do the job, but if you were feeding the steam into a Big Reactors Turbine you weren't really concerned.
From what I've seen in 1.10, the AA Lava Fabricator is priced out of the market with power overhead, which is probably why it has the cost it does. The Magma Crucible can still make lava at a semi-reasonable cost (cheaper if you have a supply of Netherrack, but that imposes it's own problems), but without the MFR Steam Boiler to convert it to steam, it's hard to get a positive net power.
There was a way to get a net positive using the Lava Fabricator and an EnderIO Stirling Generator at one point. Not sure how the margins trimmed out on that - maybe the Magma Crucible could fill the gap if fed a steady supply of Netherrack, but again, that comes with it's own challenges.
