WPML - Gravity Forms Multilingual v1.3.13 DEMO
You can use any contact form plugin and simply create different forms, per language. So, what's the benefit in translating the same form to different languages? The reason is convenience.
Setting up a form may be a complex process. Often, you may want to include logic for notifications, validation and other "behind the scenes" settings. Additionally, it's often easier to insert a single "contact us" form into your content, without having to worry about what form in which language you are inserting. WPML lets you create one set of forms with Gravity Forms, in your language. Then, you only need to translate the texts that appear in the forms and WPML will display the form in the right language. It's the same form and any changes you do on it will apply instantly to all languages.