The Frenchman moved into the semi-finals with a 7-6 (8) 6-3 victory over the Australian.
Simon, seeded second at the event, had looked in danger of blowing the first set in the tie break as he let a 5-1 lead slip before finally taking it 10-8.
He was 4-1 up in the second set when the players had to leave the court after a shower, but he return to complete his victory.
He will next face Italy's Andreas Seppi in the semi-final. The seventh seed booked his last four place with a 6-4 6-2 win over Radek Stepanek.
The other semi-final will be an unseeded affair between Ivan Dodig and Feliciano Lopez.
In 's-Hertogenbosch, second seed Stanislas Wawrinka is the only seed left in the competition after he enjoyed a 6-4 7-6(2) win over fifth seed Jeremy Chardy
ATP Eastbourne quarter-finals
2-Gilles Simon (France) beat Bernard Tomic (Australia) 7-6(8) 6-3
7-Andreas Seppi (Italy) beat Radek Stepanek (Czech Republic) 6-4 6-2
Ivan Dodig (Croatia) beat 8-Fabio Fognini (Italy) 6-3 6-2
Feliciano Lopez (Spain) beat Fernando Verdasco (Spain) 6-4 7-6(6)
ATP 's-Hertogenbosch quarter-finals
Xavier Malisse (Belgium) beat Roberto Bautista (Spain) 6-4 6-4
Nicolas Mahut (France) beat Evgeny Donskoy (Russia) 6-3 7-6(1)
2-Stanislas Wawrinka (Switzerland) beat 5-Jeremy Chardy (France) 6-4 7-6(2)
Guillermo Garcia-Lopez (Spain) beat Jan Hernych (Czech Republic) 6-4 6-1