Would you care if Trump lied?
I would care - but that's a matter between him and the IRS. If they think he lied - then they will prosecute his ass. With regards to his taxes, they are the only authority that matters. He can say whatever he wants to the public and I don't care at all.
Render unto Caesar...
As others have said, lying about how much you made is the most boneheaded of ways to minimize your taxes. Most do not involve lying at all.