Dumbledore never planned for him to survive. He wanted Harry weak. Albus Dumbledore was considered the greatest wizard for many decades after defeating Grindelwald, But in 1981 the wizarding world began considering Harry more powerful for being able to defeat the Dark Lord. Even back then Dumbledore knew about the Horcruxes, or at least about the one in Harry's scar and he did nothing, he used the next decade to plan. Voldemort would kill Harry, this way the Horcrux will be destroyed as well, then Dumbledore would jump in and kill Voldemort while he would be mourning young Harry and the wizarding world would celebrate him again and follow his lead. 