There are two different exports Google CSV format and Outlook CSV format when using the standalone contact manager. (you didn't say if you are using that or directly from Gmail)
There are some known issues with the Google CSV format (for example birthday and additional data don't get exported) therefore I would try:
1) Make sure you use the Outlook CSV format
1) The two Description fields (Section 1 - Description, Section 2 - Description) must be populated with the word Personal (initial cap counts!) on each and every row if you want the data in the 10 fields that follow to be included in your Import. If you have no data in the Section 1 - Description field, then the data in that row following will not be imported AND the data in the fields following Section 2 - Description will be imported instead if the Section 2 - Description field is populated with Personal. If you put another word in, rather than Personal, the data will import, but each field in the row will be appended with that word. So, if you use the word Business, your data for the Google Contact for that row will be included, but renamed (i.e., (213) 555-1212 Business / mobile). As a result of this, when iPhone tries to upload this field, it will not be recognized as a phone number and will be left out or included in the Note section.
2) If you remove any fields (columns) from this format, the Google will only look for and populate: name, email addresses and notes.
3) Most contacts CSV formats separate First Name and Last Name. Not Google's. You have to concatenate (just learned this function) the two fields into one, first. (See below Note B.)
4) If you are importing a lot of contacts (I have >2500), it takes Google a while to update the Contact Manager screen. Even though it says it's done, there is nothing there. In my case, I figured 2500 was too much, so I tried importing again with a new CSV file with only 400 records. The import of the 400, five minutes later, was rejected because, it turns out, the 2500 were there all the time.