Complex sentence: Refusing to back down, Walt demands that Declan say his name, and when Walt insists that Declan already knows and informs him that it was he who killed Gus Fring, Declan resignedly realizes and acknowledges Walt as Heisenberg.
Split into simpler sentences: Refusing to back down, Walt insists that Declan already knows, and demands that Declan say it. When Walt informs him that it was he who killed Gus Fring, Declan resignedly realizes, and acknowledges Walt as Heisenberg.