I'd say the evidence is spotty at best.
First, KOREA was colonized by Japan, as in the whole peninsula. The area that would become South Korea was neglected fairly heavily by Japan. Ports at Busan and Incheon, as well as the Gyeongbu and Jungang train lines are really the extent to which the Japanese helped the South. Northern Korea on the other hand got hydro-electric dams, factories, and other heavy industry. Part of this is that southern Korea is, relatively, flat and suited for farming while northern Korea has many more natural resources to be exploited in heavy industry. The other part is that Korea was used as a base for the Russo-Japanese War and the Sino-Japanese War(s) and as such, having factories in northern Korea and Manchuria was strategically a better choice.
Now, with that in mind, the Korean War resulted in the US completely decimating North Korea through aerial bombing. A huge part of the advantage that the North had from the Japanese was destroyed. Still, it wasn't until between 1978-1983 that South Korea overtook North Korea economically.
The only "benefits" of colonization by Japan was that Korea was forced to modernize. However, the Korean Empire (1895/7-1910) had already begun modernization efforts. Many historians speculate that had that modernization begun only a few years earlier, Korea would have been able to fend of the Japanese.
The real help that Japan provided was a result of colonization. It was the reparations made during the 60's. Park Chung-hee and Kim Jong-pil (the prime minister, CIA head, PCH henchman) negotiated for technology transfers and no-interest loans from Japan that made it possible for South Korea to create POSCO, invest in the chaebols, and build the Seoul Subway system. These particular investments are the foundation for the South Korea that we know today.
TLDR - colonization didn't help, but reparations for colonization did.
sources - A History of Korea, Kyung-moon Hwang, Palgrave Macmillan, 2010.
There is a whole series of interviews with Kim Jong-pil in the Joongang Daily, a local newspaper. Fair warning, Joongang is a right-wing paper and Park Chung-hee and Kim Jong-pil were right wingers, so take it with a grain of salt. That said, this link is to the article where he talks about getting 800 million from Japan to build POSCO and the Guro Industrial complex, which is about 2 miles from my house.
http://koreajoongangdaily.joins.com/news/article/article.aspx?aid=3004343
it's not it's it's its