Its not.  It isnt even possible to have that be provably fair and any claim as such is just a total lie because its missing the client seed.  You cant have provably fair without a client seed.  Besides,  that lottery is garbage anyway,  dont even bother trying to play it.  You will never win it.  You have about as much chance as winning the power ball which would provide you a way larger return.

Idk what a btc hash has to do with anything,  unless the seeds it uses are give  ahead of time and the 1st btc hash after a specified time is used.  I have not seen where any of those are provided and judging from theQuinN's snarky reply, they likely dont exist or he would have simply provided that link like any normal person would do.