The speaker is out of money and looking for somewhere to go, and "a cell" hints at a place to hide, sleep, or be locked away. The poem is tiny, and that bareness fits the situation: there is almost nothing here, just a few short lines of someone running low.
The strangest image comes in the middle. A "brave press of confidence" might help the speaker, but the result is "ice in an oven," something that can't last. It suggests that any confidence they put on would melt quickly under the pressure of their circumstances. The word "gin" could point to the drink, or to a trap, and the poem leaves both readings open.
The ending is flat and quiet: "I drink and talk." There is no solution, only a small, habitual act. The mood is tired, wry, and a little numb, as though the speaker has stopped expecting rescue and is simply getting through the moment.