A 2-1 defeat at Exeter on Saturday left the Os in eighth spot, five points off a play-off place with four games remaining.
But Slade is optimistic of Orient's chances, telling the London Evening Standard: "I believe. I just need the players to believe in themselves more.
"I believe little old Orient can get in the top six. I got little old Yeovil into the top six, so why not little old Orient?"
Source: PA
Source: PA