Usually I am clicking on a link in my gmail account
Using the Gmail app?
I rarely use that app, prefering the Mail app; but this is how it is supposed to work.
Tap the menu icon at the top left to see all the mail boxes, etc.
Go to the bottom of the list and choose Setttings,
Then choose Google Apps.
In the Open Browser In section make sure the slider is off (to the left)
And that your browser of choice is checkmarked.
If that is how it is set up, and it is still not working properly then it's likely an issue with the Gmail app. You can try forcing it closed (double click the Home button then swipe up on the Gmail app's preview), or resetting the iPad (Hold down the Home and Power buttons until the Apple Logo appears.