Welcome, Tiu. I am Cory.
Unfortunately, Uber does not sell gift cards anymore. If you want to pay for a ride of another person, you would have to add your credit card to the account.
If you do not want to do that, then you can setup an event here. - https://event.uber.com/ by setting up the event, you can setup trips and how much you will pay per trip.
If you need a step-by-step guide, you can go here. - http://www.wikihow.com/Give-Uber-Credit-As-a-Gift
While they do not offer gift cards, Uber Events is another practical solution to fit the needs of paying for a ride or rides of someone else.
I hope I have answered your question today.
Please let me know if this answers the question you are asking.
I am following up with you to see if you were able to use the Uber event feature to pay for rides.
Let me know if you have any other questions.
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