No reference to the child later on, also you see more children at the start, and only one during your escape process, but you leave him behind rather quickly.
General Tullius also says very few made it out alive, that doesn't mean the child didn't, but it doesn't mean he did either. No children can be found at the orphanage that reference Helgen either. Seeing however as Riften has the only orphanage in Skyrim the logical conclusion would be that the children died or had family outside of Skyrim that picked them up.
The kid from Helgen is alive and well, and he is even with someone who starts and interesting quest line
Really? Had no idea, can you post where in spoiler tags? Really curious now.