Would I be taxed on money gift from abroad? Consider the amount is larger than 100k. If yes, what is the rate? If no, do I still have to file some particular tax form on it as well?
It turns out that you must report it.
"The IRS requires U.S. taxpayers to file Form 3520..."
Unsurprisingly there are a number of "traps" ..
"For example, foreign family members should not make “gifts” to their U.S. family members from a foreign corporation, since the IRS will consider such transfers to be taxable corporate dividends that cannot qualify as tax-free gifts."
"However, separate IRS regulations require recipients to report a foreign cash gift. IRS Form 3520 is required if you receive more than $100,000 from a nonresident alien or a foreign estate. In addition, gifts from foreign corporations or partnerships are subject to a lower threshold that is adjusted for inflation each year. For 2016, gifts of more than $15,671 trigger the filing requirement. You won't owe any tax as a result of filing these documents. However, failing to file them can result in IRS penalties."
You can google many entries on this.