Btc is really dependent on stablecoins like USDT, TrueUSD and to so on. If these coins are liquidated, btc will have a harsh time, as major trades happen on stable coins/btc pairs.
I don't know for sure, but in my opinion, fiat has an influence on Bitcoin because Bitcoin is a currency that is directly related to the value of fiat so I think there is little effect though.
but it could be if Bitcoin is independent because Bitcoin has a different market than Fiat.