The opposition probably is winning in Istanbul, but that’s about it.
The opposition in Turkey is quite angry about graft in the rebuilding of Turkey after the last earthquake in northern Turkey which includes Istanbul. Given the destruction and death from newer buildings in southern Turkey, there may be a lot of anger there too.
In the US counting in cities is often slower because of numbers, but also more liberal. It may take longer for votes to be delivered from the stricken south. In addition there was a large number of Turks voting in other countries, although I think the deadline for turning in those votes was a few days ago. A lot of possibilities for a slow vote count, and opportunities for fun and games too perhaps.