A bill to limit Friday's scheduled 10 percent income tax cut to a maximum of $720 per return appears headed for certain defeat in a Senate vote today, despite arguments from congressional Democrats that it offers a fair way to raise half of the $12 billion in new revenue Congress committed itself to find under the 1984 budget resolution.

The Republicans, who control the Senate, appear to be lined up solidly behind President Reagan, who has promised to veto any bill tampering with the tax cut, and Finance Committee Chairman Bob Dole (R-Kan.), who is leading the floor fight against the bill.

Even Sen. Dale Bumpers (D-Ark.), a leading proponent of the bill, acknowledged that the Democrats lack the votes to pass it. He predicted one or two Democrats will join the entire Republican majority in voting to kill the measure.

The bill, which passed the House last week, would limit to $720 the tax reduction that any taxpayer would get as a result of the third year of Reagan's 25 percent personal income tax cuts. All taxpayers still would get a reduction when withholding rates are adjusted on Friday, but about 8 million of the 95 million filers--mostly with family incomes over $50,000--would have their reductions reduced.

Dole, who dismissed the measure as "folly," says he wants no change in tax liability for individuals until Congress has reviewed all the "loopholes" and special-purpose tax breaks in the present law.

His committee began hearings yesterday on "tax expenditures," or tax losses to the Treasury from the myriad special-purpose deductions and credits in the law.

At Dole's request, Alice Rivlin, director of the Congressional Budget Office, listed some that could be curtailed to cut the 1984 deficit, among them eliminating the deductibility of state and local sales taxes, lengthening the depreciable life of buildings from 15 years to 20, and limiting consumer loan interest deductions.