Do they last for just 5 turns or does they last for the whole battle?
Entry hazards last until Rapid Spin / Defog are used, Or with Toxic Spikes, You can send in a Poison type Pokémon to get rid of them.
Source- Experience and research on entry hazards.
It lasts the whole battle or until someone uses Defog or Rapid Spin. EDIT-
>Or sends in a poison Pokemon for Toxic Spikes commented 5 hours ago by Meewec
Source-Experience
they last for the whole battle unless someone uses rapid spin or defog