There are definitely choices he can pick today to use those lenses, with varying compromises. Much will depend on what mount those lenses are. If the lenses are Pentax K mount or Nikon mount lenses for example, they can still be attached to current Pentax or Nikon DSLRs - some cheaper camera bodies won't have as much flexibility in use or settings, and others will...so check on which bodies would be best with the old manual mounts first from others who shoot with those brands.
Other brands, such as Canon, Minolta (now Sony), Olympus, etc have changed their camera mounts when they went to Autofocus in the late 80s, or again when they went to digital (Olympus converted over to their 4:3 format)...so those DSLRs don't have backwards compatibility with older manual lenses...it's a completely different mount and won't fit on the new bodies.
However, there ARE still options for Canon, Minolta, Olympus...and actually ANY other lens mount ever made: the class of cameras known as 'mirrorless interchangeable lens' cameras have a special design eliminating the mirror from the body, and narrowing the lens' registration gap to much smaller than any other 35mm or Rangefinder mount...in other words, the lens sits much closer to the sensor (or film) than any other camera in history. The advantage of that is that you only need a cheap metal 'spacer' adapter to move the lens out to the right distance from the sensor to be able to properly focus, and voila! You can use any old lens from any mount ever made. Mirrorless cameras with larger sensors are made by Canon, Sony, Samsung, Olympus, Fuji, and Panasonic. Some have 'APS-C' sized sensors which would add a crop factor to those old lenses...usually 1.5x...which means a 50mm lens will look like a 75mm lens, a 24mm lens will look like a 36mm lens, etc. Some have 'M4:3' sensors which are a little smaller, and therefore have even more of a crop factor of 2x...so the 50mm lens looks like a 100mm lens, and so on. And recently, some new mirrorless bodies have just debuted which use a full frame 35mm sensor just like those old film cameras...so a 24mm lens = 24mm, 50mm=50mm, etc. Most of these mirrorless cameras can perform in full manual mode, where you set every parameter, and most an also shoot through these old lenses by metering through the lens, allowing you to use them in Aperture Priority mode, letting the camera choose shutter speed or ISO as needed. Some of these mirrorless cameras have manual focusing aids which can help you focus more easily by providing visual indicators of what parts of the frame are in focus (called Focus Peaking). Some of these mirrorless cameras come with viewfinders and some without - the viewfinders are electronic rather than optical since there is no true optical path from lens to viewfinder...these viewfinders range from basic small LCDs to very high resolution OLED finders that are quite large.
I have a DSLR, but also shoot with a Sony NEX-5N mirrorless camera, with an electronic viewfinder attached. The NEX is an APS-C sensor, so there is a crop factor of 1.5x with old manual lenses. It has focus peaking, and can meter through the lens so I can use priority or manual metering modes. I use my NEX with several different older mounts - I have Pentax K-mount lenses, Konica K/AR lenses, and Leica M-mount lenses. Each uses a cheap non-electronic adapter - mostly ranging in price from $20-30. I've got lenses from the 1980s, 1970s, and 1960s, made by Vivitar, Soligor, Rokinon, Osawa, Pentax, Konica, Chinon, and Voigtlander. All work beautifully on the mirrorless body - as simple as can be...most of the time I shoot in Aperture Priority - I set the aperture on the lens, focus, and the camera can pick the shutter and ISO. If I want more control, I switch to manual and set the shutter speed on the camera body, aperture on the lens, and ISO in the camera, then focus and shoot.
So if you have old Nikon mount lenses, you can consider either a Nikon DSLR or the mirrorless bodies. If you have Pentax mount lenses, you can consider a Pentax DSLR or the mirrorless bodies. And if you have any other mount, you can consider the mirrorless bodies.
Hope that helps!
Sony DSLR-A580 / Sony 18-250mm / Minolta 50mm F1.7 / Sigma 30mm F1.4 / Tamron 10-24mm / Tamron 200-500mm / Tamron 90mm F2.8 macro / Minolta 300mm F4 APO
Sony NEX5N / 18-55mm F3.5-5.6 / 55-210mm F4-6.3 / Pentax K adapter / Konica K/AR adapter / bunches o' Konica & Pentax lenses!