The directory that you checked the pocketsphinx code out into needs to be on your ROS_PACKAGE_PATH. To quickly check if this is your problem, cd into wherever you checked that SVN repository out into and type
export ROS_PACKAGE_PATH=pwd:$ROS_PACKAGE_PATH  In the same terminal window, try rosmake --rosdep-install pocketsphinx. If the package still isn't picked up, try running rospack profile and then the rosmake command again. If it doesn't work yet again, update your question with the steps you executed in order and any further error messages. The directory that you checked the pocketsphinx code out into needs to be on your ROS_PACKAGE_PATH. To quickly check if this is your problem, cd into wherever you checked that SVN repository out into and type export ROS_PACKAGE_PATH=pwd:$ROS_PACKAGE_PATH

In the same terminal window, try rosmake --rosdep-install pocketsphinx. If the package still isn't picked up, try running rospack profile and then the rosmake command again.
If it did fix the problem, you can add a line similar to the one above to your .bashrc file such that that path is always on your ROS_PACKAGE_PATH. Note that in your .bashrc file, you'll have to use the actual path, not the pwd shortcut that worked above.