Update your firmware to 1.6.0
Please go to TREZOR Beta Wallet to update your device firmware. Note that for the time being, your Bitcoin Gold wallet will only be accessible from the TREZOR Beta Wallet.
Make sure you have your recovery seed accessible, in case you are asked to recover your device after a firmware update. Never update firmware without your seed nearby.
Make sure your firmware is updated to 1.6.0 before you start the claiming process.
Select the account type from which you want to claim your bitcoin gold — either standard account (SegWit enabled) or legacy account.
Click on Connect with TREZOR and authenticate yourself in the TREZOR Connect window. Let it run the discovery process. Depending on the size of your accounts, this may take a minute.
Select an account with a positive BTG balance. Input an address in which you want to receive your BTG. The default address is taken from your TREZOR, but you can enter any BTG address.
Bitcoin Gold addresses start with either A or G as the first symbol.
Click on Claim amount, and confirm the transaction in TREZOR Connect. The claim tool will refresh and you will see a Transaction successful banner. Now you can repeat the process for your other accounts.
Open Bitcoin Gold Wallet
Go to TREZOR Beta Wallet and authenticate yourself. (If you do this immediately after claiming your BTG, your TREZOR is already unlocked — no need to enter PIN.)
In the upper left corner, click on the currency selector and choose Bitcoin Gold (BTG). You will be brought to your BTG wallet, first account. If you claimed BTG to this account, the transaction would appear here.