To identify how many people took your survey in a different language, you'll need to build a new segment at the same time that you create the survey in another language.
Once you've built your custom link, make sure to select "create a new segment" from the Add visitors to segment drop-down menu.
Type the name of your segment in the Segment Name text box that appears below.
You can use this custom link to direct participants to a language-specific version of your survey. You can do this multiple times for as many languages as you need. French, Russian, Japanese, you name it!
Note: It will take a couple of seconds to translate your survey from the default language (English).
When your survey is complete, you can filter your results and identify how many people completed the survey in each different language.