You can make use of the iCloud to transfer contacts to gmail: Step 1. Tap Settings > iCloud, sign in with your iCloud account. And swipe Contacts to ON.
You can transfer contacts from iPhone to Gmail either via iPhone, Google Drive, iTunes, or iCloud. It all depends on the method you choose to use. Part 1: Transfer Contacts from... · Part 3: Import Contacts from...
Open your iPhone or iPad's Settings app. · Tap Contacts and then Accounts. · Tap your Google Account. · Switch Contacts on. · Tap Account and then Advanced.