I am a relatively new jazz player. I do know a sizable amount of theory, though. My question was if there were any tips and advice you could give me concerning if and how soloists try to adjust their solo to the rest of the ensemble (specifically piano). I have always heard the mantra that one should listen to the rest of the ensemble while playing. What I don't know exactly is what to quite do with that information. Like for example, how should I take in account what chords the piano player is playing and adjust my solo, if I should at all.
"Listen to the rest of the ensemble" applies all the time when you are making music and not just when you are the soloist.
If you are playing a jazz solo ideally the other players are listening to you and trying to accompany you. What you you do with the information you get by listening to the others is up to you. You will want to make sure that you're in time, and in tune, and that what you play fits the harmonies. Of course you have to take into account what chords the piano player is playing, but maybe he's giving you melodic ideas too. Maybe the drummer is playing a rhythm you can use. You might even get into a musical dialog with them.
To a beginner, jazz might seem random, just a bunch of random notes played by an instrument, followed by the same thing by the next instrument. But it's not! Each jazz song has specific chords that form a form. Take a look at this classic jazz standard Lullaby of Birdland:
You can see that the chords are very specific. These are the chords everyone is improvising on. The first step musicians take is learn the chords and improvise on top of them; usually this might be done as homework. When they meet with other musicians to play, they will use this form as a carpet to step on. They will start playing changes on these chords, possibly without really knowing what the other musicians will play and while doing that they will listen to the rest of the ensemble to hear what they are playing and musically-communicate with each other.
Like for example, how should I take in account what chords the piano player is playing and adjust my solo, if I should at all.
This depends on your ear training. When you have a 4-voice chord like Abmaj7, the pianist won't necessarily play all four notes of it. If you can listen to the voicing and figure out which notes are missing, you can fill in those. OR the exact opposite. You can follow the notes the pianist is playing. Keep in mind though, that the pianist must follow the soloist as well. It's a two way street.
Listen to what scales the pianist is using, because jazzists quite often use different scales and modes for each chord. You can listen to what they are doing and use them in your solos.
Another really important thing you should do is to listen to the rhythmic patterns the pianist is playing. They will change quite often and you can pick them up and use them in your solos.