If you're having trouble turning on the Bitmoji keyboard, there are a few things you can check. First, make sure that the keyboard is enabled in your device's settings. To do this, go to Settings > General > Keyboard and tap the toggle switch next to Bitmoji.
If the keyboard is still not working, try restarting your device. Sometimes all it takes is a reboot to fix the problem.
If you're still having trouble, there may be an issue with the app itself. Try uninstalling and reinstalling Bitmoji from the App Store.