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I recharged my Lisboa Viva in July 2017 at one of the automatic ticket machines in the Lisbon Metro with a UK debit card. So yes it is possible to use non-portuguese cards in these machines.
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According to the details on Metro Lisboa, credit cards can be used at ticket offices and automatic ticket vending machines. However, in some stations, tickets can only purchased at automatic vending machines and, as noted, only accept the Multibanco, a Portuguese debit card.
Multibanco is the single unified interbank network in Portugal, linking ATMs of all Portuguese banks, so some debit cards may work.
Although inconvenient, you should be able to find a nearby ATM (probably Multibanco), where you can get Euros to use in the ticket vending machine.