From experience Turkey's tourism to both the beach resorts, and Istanbul sadly does get affected with downturns in bookings when security and unrest occur not just in Turkey, but also in the surrounding ME and the Gulf regions.
Folk do get nervous and will stay away and book elsewhere - the past few summers have shown that with 50% down in 2015 and 2016.
Few Western tourists now visit IST compared to 5 or so years ago.
UK Cruise ships no longer call in to Istanbul (a Jewel of a city to visit) nor also at Kusadasi (for Ephesus) - The UK cruise lines have simply pulled all their ships out of Turkey.
But Brexit uncertainty saw a huge rise in summer 2019 bookings to Turkey BUT that was lost with the loss of 800000 future bookings due to the collapse of Thomas Cook.
Jet2 obviously hope to pick up plenty of that potential business for summer 2020 but Turkey still remains a volatile destination.