Is the dallas airport being affected by hurricane Harvey (flight cancellations/delays)

Dallas generally has been unaffected by the hurricane, as it is hundreds of miles away.

Most Houston airport flights are being rerouted to Dallas, but Dallas itself hasn't been experiencing terrible weather conditions

I'm sure it is. I'm not there now.

Yes, I had an arriving flight yesterday Sunday 27, that was delayed by an hour and a half and the departing flight by one hour.

Check the airliners website.