Yes, guru is commonly used in the US to refer to someone very knowledgeable about a subject.
Our language (American English) is very adept at absorbing words from other languages. Another example is "honcho" from Japanese meaning group leader. In WWII , American soldiers brought it back with the same meaning. Today, in the US, it is quite common to refer to someone as the "chief honcho," meaning the person in charge. The list of originally non-English words included in everyday speech is quite large.
John