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I know that radio telescope can 'see'* further than an optical telescope but I would like to know how much further? (let's say the optical has a magnification of 50x and the radio has a dish of 90m in diameter).
*When I say see I mean how far into space image wise.

Some Random Awesome Guy
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    You've seriously misunderstood how telescopes work. One telescope cannot see further than another and their ability to see things has nothing to do with their magnification. The quality of a telescope which is important is its light collecting ability. – zephyr Jun 13 '17 at 13:12

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Radio telescopes cannot "see further" than optical telescopes but electromagnetic radiation in the range detected by radio telescopes may come from a further distance (i.e. from an earlier time) than detectable by optical telescopes and/or radio waves may penetrate things which are obscured at optical wavelengths.

The classic example of the first case is the cosmic microwave background (CMB) - actually the oldest detectable radiation in the universe (assuming our cosmology is even half-close to being right). This is the radiation that was emitted when the early expanding universe cooled just enough to allow hydgrogen atoms to form - the captured electrons gave off radiation and the universe's density was no longer great enough to ensure that radiation caused a balancing ionisation. That happened so long ago/so far away that it now looks like something very cold (about 3 degrees above absolute zero) and so is not detectable at visible wavelengths but is at microwave wavelengths.

The second case includes things like radiation from dust clouds in our galaxy - the dust blocks visual radiation but not radio waves.

But the premiss of your question is wrong in that it is not a question of dish size and certainly not magnification (the correct parallel with an optical telescope is also dish - or rather lens or mirror - size incidentally.)

adrianmcmenamin
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