China could theoretically put a large combined arms force onto shore on Taiwan.
High end estimates are that by 2025-2026 China will have sufficient amphibious sea lift and landing craft to put 30,000 to 45,000 troops and their equipment on Taiwan within a 2-3 day period. Low end estimates are that sea lift would be sufficient for a force of 16,000 to 20,000 troops in a 3-4 day period.
The question is whether its worth the cost, and whether it could support those troops once they've arrived.
At present, the answer to the cost would be 'most of China's brown water navy', 'some of China's blue water navy' and 'more than half of the troops put on the island', along with sundry damage to Chinese port facilities within about a 500km radius of Tawain (and, that's without US involvement).
Taiwan has an inventory of around 1200-1400 anti-ship missiles, a mix of locally developed systems and the US Harpoon on a combination of sea and land launchers. These act as the country's primary deterrent against invasion - estimates are that these would be sufficient to sink somewhere in the range of 200-500 Chinese ships. Taiwan also has a smaller inventory of short-range ballistic and cruise missiles which would target Chinese ports, particularly embarkation and supply points.
The answer to supporting the troops is a qualified no. The PLAN doesn't have sufficient sea lift to support a large and ongoing amphibious operation against Taiwan (and likely won't have any such capability for more than a decade, given declared Chinese ship building intentions).
However, there is enough commercial shipping that China could requisition to support a cross-Straits invasion of 160,000+ troops. At present, there is better than 900,000 tons of RO-RO ships that could have dual civil/military use. The only problem is that these ships would be hideously vulnerable to any sort of hit from a missile (or even something like a tank or artillery round) - look at the lessons from the sinking of the Moskva.
