It can’t because the future doesn’t exist yet.
But Tarot readings can analyze the status quo, and the status quo is the seed of the future.
For instance, a psychological Tarot reading can identify that the querent is an anxious person. And anxiety attracts scary situations. If the Tarot reader told the querent that she would get into scary situations, the Tarot reader is likely correct, but she didn’t really predict the future.
We also need to consider that history rhymes. History moves in circles (the Wheel of Fortune) and principal events reoccur like economy crises. But we never know how the re-occurence will look like.
For instance, an experienced farmer can predict a storm. But he can tell only that a storm will come, not when and how strong it will be.
The last thing we need to consider are karmic seeds. We receive karmic seeds at birth, which may hatch or not, depending on how your life goes. A Tarot reader, if psychic, can read karmic seeds that are about to hatch, for example, that the querent is about to meet her soul mate. But then again, the Tarot reader didn’t predict the future but the seed of the future, which is in the present.