From reading several Tegra X1 spec sheets and information from several devs and the Tegra Shield, All I could conclude is ">512" where some numbers where even 4096, enough to blow one for every system update to come for its entire lifetime atleast..
Edit for extra information:
The fuses themselves are not conventional fuses like people think of, its basically a ROM chip thats writeable once.. so it could have 64 bytes worth of fuses, 128, 256, 512.. etc, I never could find the exact size.