Futures and spot markets, in the absence of carrying costs and cashflow from underlying, should in principle be mathematically related by this formula: futures price=current spot price of underlying x (1+risk free rate)^tenor. Arbitrage activities should take place based on this mathematical relation.
However in the crypto market which is largely unregulated now, we think compliance issues make it difficult for these new institutional monies to enter the spot market. This mean the usual arbitrage activities cannot take place and therefore spot prices are likely to move independently from futures prices. As you rightly pointed out, sentiments could be a link between the 2 markets.
This is my analysis on the impact of BTC futures summarised into 5 points. Like to hear your views.