Tariffs are paid by the consumers of imported goods, not by the importers themselves. Costs are simply passed down as higher prices. The idea that an importer would absorb the tariffs doesn’t hold water.
No, the cost of a tax on trade is always split. The way it is split is determined by elasticity of demand and elasticity of supply. In this particular case, Chinese suppliers have been paying about 83% of the tariff.
If I recall correctly from an economics class yay days ago, it doesn't matter if the seller pays the tax or the buyer -- the effective cost is shared (fewer buyers too).