Where can I confirm that my HTC One XL is evita model? I want to double check that my HTC One XL is evita model. 

I am almost sure I saw it in a menu somewhere but I cannot find it anymore.

Could somebody guide me where I can find such info?
According to the Wikipedia article, all the HTC One XL devices fall under the Evita model. Evita is just the code name for the device. Just about every device is initially manufactured with a "codename". This is more just like an internal name for the device. This could be because they have not decided on a "public brand" for the device yet, or just because they want to call it something else internally.

Sometimes the codename resides in the model name in the Settings -> About Phone. But if you have adb access to your device, you can do something like:

&gt; adb shell
$ getprop


this will dump out all the properties that are configured during the boot process. one of them, probably something like ro.product.device will contain the value evita.