This is circular. I don't think anyone denies he falsified/lied on the form.
That is a crime. How it is handled is a separate issue. I'm not sure of course what is left to investigate, beyond various allegations by Republicans.
Weiss's office said in a statement: "Hunter Biden received taxable income in excess of $1,500,000 annually in calendar years 2017 and 2018. Despite owing in excess of $100,000 in federal income taxes each year, he did not pay the income tax due for either year."
Regarding the gun charge, the statement said that "from on or about October 12, 2018 through October 23, 2018, Hunter Biden possessed a firearm despite knowing he was an unlawful user of and addicted to a controlled substance."
Weiss's office also said its investigation continues.