To optimize Twilio IVR flows, A/B testing tools like Optimizely can be used to experiment with different voice messages and analyze their effectiveness. The tutorial demonstrates how to set up an Optimizely project, create an A/B test, and configure Twilio functions to split traffic and send events to Optimizely for reporting purposes. The tutorial also covers setting up a Studio IVR flow using the Optimizely SDKs, configuring the flow to capture survey results and send them to Optimizely, and troubleshooting common issues that may arise during testing. By following this tutorial, users can learn how to use Optimizely to optimize their Twilio IVR flows and improve user experience.