One of the biggest hints towards Ishida's feelings for Orihime, in my opinion, is his eyes - especially the last handful of chapters we saw him in. I've noticed that when he's interacting with anyone other than Orihime, his eyes are narrow, sharp, and intense. But the moment he looks at Orihime, even for a moment, his eyes kind of widen a little and they soften significantly. When addressing her, he always lightens and relaxes his demeanor very perceptibly, and I can't help but think that those who choose to ignore that and say its nothing are in denial.