Gemini releases a statement indicating their plans for the timeline around August 1st:
Beginning at 6:00 p.m. EDT on Monday, July 31, 2017 (22:00 UTC), Gemini will temporarily disable all bitcoin withdrawals and crediting of deposits in advance of any Bitcoin hard and/or soft forks. Both USD and ether deposit and withdrawal functionality will be unaffected.
We will resume allowing bitcoin withdrawals and crediting deposits after we believe the Bitcoin Network has stabilized, which is anticipated to be sometime Wednesday, August 2, 2017 (EDT). Gemini users may still trade bitcoin on our BTC/USD and ETH/BTC matching engines and participate in our BTC/USD auctions while bitcoin deposits and withdrawals are temporarily disabled.